{"draftJsState":{"blocks":[{"data":{"image":{"id":"69db55b7fd89f75468682ae8"}},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"картинка взята с сайта ya.ru","type":"atomic:image","key":"6v3ml"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Иллюзия величия: Почему примитивы умеют вызывать методы (и как это работает)","type":"header-two","key":"ff0j5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Вы когда-нибудь замечали странность?","type":"unstyled","key":"a9o27"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"96d2v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":53,"style":"ITALIC"},{"length":7,"offset":110,"style":"ITALIC"},{"length":9,"offset":168,"style":"ITALIC"}],"text":"const str = \"hello\";\nconsole.log(str.toUpperCase()); // \"HELLO\"\n\nconst num = 42;\nconsole.log(num.toString()); // \"42\"\n\nconst bool = true;\nconsole.log(bool.toString()); // \"true\"","type":"unstyled","key":"16o92"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Вроде бы ничего удивительного. Но подождите. \"hello\" - это же примитив, строка. У примитивов не может быть методов! Или может?","type":"unstyled","key":"4cj2t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Добро пожаловать в одну из самых элегантных иллюзий JavaScript - механизм, который заставляет примитивы вести себя как объекты. Это не магия, это тщательно продуманная система объектов-обёрток.","type":"unstyled","key":"aoquf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Великий парадокс: примитивы без свойств","type":"header-two","key":"6q97l"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Начнём с основ. В JavaScript есть примитивы: string, number, boolean, symbol, bigint, null, undefined.","type":"unstyled","key":"c09qs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"15j9f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":36,"offset":47,"style":"ITALIC"},{"length":28,"offset":110,"style":"ITALIC"}],"text":"const str = \"hello\";\nconsole.log(str.length); // 5 (откуда? у строки нет свойств!)\nconsole.log(str.unknown); // undefined (но ошибки нет)","type":"unstyled","key":"fq5ra"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"У примитивов не может быть свойств. Попробуем добавить:","type":"unstyled","key":"3p7i3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bup8c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":70,"style":"ITALIC"}],"text":"const str = \"hello\";\nstr.newProp = \"world\";\nconsole.log(str.newProp); // undefined (не сохранилось!)","type":"unstyled","key":"6989p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Но почему же тогда str.length работает? И как мы можем вызывать str.toUpperCase()?","type":"unstyled","key":"6kirv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. Объекты-обёртки: Тайные помощники","type":"header-two","key":"2pcge"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"За кулисами JavaScript создаёт временные объекты-обёртки, когда вы пытаетесь обратиться к свойству или методу примитива.","type":"unstyled","key":"9i9tf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"c39p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":22,"style":"ITALIC"},{"length":48,"offset":64,"style":"ITALIC"},{"length":39,"offset":113,"style":"ITALIC"},{"length":38,"offset":183,"style":"ITALIC"},{"length":35,"offset":257,"style":"ITALIC"},{"length":32,"offset":293,"style":"ITALIC"}],"text":"const str = \"hello\";\n\n// То, что вы пишете:\nstr.toUpperCase();\n\n// То, что происходит на самом деле (упрощённо):\n// 1. Создаётся временный объект String\nconst temp = new String(str);\n// 2. У этого объекта вызывается метод\nconst result = temp.toUpperCase();\n// 3. Временный объект уничтожается\n// 4. Вам возвращается результат","type":"unstyled","key":"ep5ei"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":0,"style":"BOLD"}],"text":"То есть \"hello\".toUpperCase() - это красивая ложь. На самом деле это:","type":"unstyled","key":"bc14g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"50b7m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"new String(\"hello\").toUpperCase()","type":"unstyled","key":"6i3bn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Три обёртки: String, Number, Boolean","type":"header-two","key":"735t8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Для каждого примитива есть своя объектная обёртка.","type":"unstyled","key":"6l806"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.1 String - обёртка для строк","type":"header-three","key":"48enm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"j3nf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":87,"style":"ITALIC"},{"length":11,"offset":128,"style":"ITALIC"},{"length":22,"offset":170,"style":"ITALIC"},{"length":29,"offset":222,"style":"ITALIC"}],"text":"const str = \"hello\";\nconst strObj = new String(\"hello\");\n\nconsole.log(typeof str); // \"string\"\nconsole.log(typeof strObj); // \"object\"\n\nconsole.log(str === strObj); // false (разные типы)\nconsole.log(str == strObj); // true (нестрогое сравнение)","type":"unstyled","key":"2upes"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.2 Number - обёртка для чисел","type":"header-three","key":"2d21i"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"e7tqj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":77,"style":"ITALIC"},{"length":11,"offset":118,"style":"ITALIC"},{"length":39,"offset":160,"style":"ITALIC"}],"text":"const num = 42;\nconst numObj = new Number(42);\n\nconsole.log(typeof num); // \"number\"\nconsole.log(typeof numObj); // \"object\"\n\nconsole.log(num.toFixed(2)); // \"42.00\" (примитив → обёртка → метод)","type":"unstyled","key":"f4eim"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.3 Boolean - обёртка для булевых","type":"header-three","key":"bg07j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3a4nm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":85,"style":"ITALIC"},{"length":11,"offset":128,"style":"ITALIC"},{"length":17,"offset":141,"style":"ITALIC"}],"text":"const bool = true;\nconst boolObj = new Boolean(true);\n\nconsole.log(typeof bool); // \"boolean\"\nconsole.log(typeof boolObj); // \"object\"\n\n// Важное отличие\nif (boolObj) {\n console.log(\"Объект всегда true!\");\n}","type":"unstyled","key":"24scv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Жизненный цикл временного объекта","type":"header-two","key":"9l8ft"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Давайте проследим, что происходит, когда вы пишете \"hello\".length.","type":"unstyled","key":"ah1i0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fte8d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":45,"offset":0,"style":"ITALIC"},{"length":49,"offset":92,"style":"ITALIC"},{"length":43,"offset":142,"style":"ITALIC"},{"length":55,"offset":217,"style":"ITALIC"},{"length":60,"offset":302,"style":"ITALIC"},{"length":44,"offset":364,"style":"ITALIC"},{"length":4,"offset":430,"style":"ITALIC"}],"text":"// Шаг 1: Вы обращаетесь к свойству примитива\nconst str = \"hello\";\nconst len = str.length;\n\n// Шаг 2: JavaScript понимает, что str - примитив\n// Шаг 3: Создаётся временный объект String\nconst temp = new String(str);\n\n// Шаг 4: У временного объекта читается свойство length\nconst result = temp.length;\n\n// Шаг 5: Временный объект уничтожается (становится мусором)\n\n// Шаг 6: Результат присваивается переменной\nconsole.log(result); // 5","type":"unstyled","key":"2l8fm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Важно: Этот временный объект живёт ровно одну операцию.","type":"unstyled","key":"2ihuf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ad7rh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":46,"offset":50,"style":"ITALIC"},{"length":44,"offset":126,"style":"ITALIC"}],"text":"const str = \"hello\";\nstr.customProp = \"world\"; // создался temp, добавили свойство, temp умер\nconsole.log(str.customProp); // новый temp, свойство потеряно → undefined","type":"unstyled","key":"ap0t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. Явное создание обёрток (и почему не надо)","type":"header-two","key":"25sjr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Технически вы можете создавать объекты-обёртки сами:","type":"unstyled","key":"81ftd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9n81u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"const num = new Number(42);\nconst str = new String(\"hello\");\nconst bool = new Boolean(true);","type":"unstyled","key":"f4oat"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":34,"offset":0,"style":"BOLD"}],"text":"Но почти никогда не делайте этого. Почему?","type":"unstyled","key":"9elcp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Проблема 1: Сравнение","type":"header-three","key":"5talc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ctn28"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":75,"style":"ITALIC"},{"length":30,"offset":126,"style":"ITALIC"}],"text":"const num1 = 42;\nconst num2 = new Number(42);\n\nconsole.log(num1 === num2); // false (разные типы)\nconsole.log(num1 == num2); // true (нестрогое, но опасно)","type":"unstyled","key":"dt8bq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Проблема 2: Булевы обёртки всегда true","type":"header-three","key":"6uqls"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cca1u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":87,"style":"ITALIC"},{"length":8,"offset":131,"style":"ITALIC"},{"length":32,"offset":173,"style":"ITALIC"}],"text":"const falseObj = new Boolean(false);\nif (falseObj) {\n console.log(\"Это выполнится!\"); // Упс!\n}\n\nconsole.log(falseObj === false); // false\nconsole.log(falseObj == false); // true (но в if всё равно true)","type":"unstyled","key":"2qikn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Проблема 3: Производительность","type":"header-three","key":"fbmlo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"itb1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":0,"style":"ITALIC"},{"length":19,"offset":102,"style":"ITALIC"},{"length":20,"offset":125,"style":"ITALIC"}],"text":"// Плохо (создаёт объекты)\nconst num = new Number(42);\nfor (let i = 0; i < 1000000; i++) {\n num + 1; // Обёртка не нужна\n}\n\n// Хорошо (примитив)\nconst num = 42;\nfor (let i = 0; i < 1000000; i++) {\n num + 1;\n}","type":"unstyled","key":"28f3v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":0,"style":"BOLD"},{"length":1,"offset":42,"style":"BOLD"}],"text":"Когда всё же нужно использовать new Number? Практически никогда. Единственное исключение - если вам нужно сохранить свойство на числе (но это странное требование).","type":"unstyled","key":"2jiei"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Методы примитивов: Полный список","type":"header-two","key":"fu9c1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 Строковые методы","type":"header-three","key":"3idah"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2tkml"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":27,"style":"ITALIC"},{"length":15,"offset":72,"style":"ITALIC"},{"length":15,"offset":111,"style":"ITALIC"},{"length":8,"offset":128,"style":"ITALIC"},{"length":4,"offset":160,"style":"ITALIC"},{"length":7,"offset":188,"style":"ITALIC"},{"length":7,"offset":220,"style":"ITALIC"},{"length":7,"offset":251,"style":"ITALIC"},{"length":13,"offset":260,"style":"ITALIC"},{"length":9,"offset":297,"style":"ITALIC"},{"length":11,"offset":330,"style":"ITALIC"},{"length":21,"offset":365,"style":"ITALIC"},{"length":9,"offset":388,"style":"ITALIC"},{"length":15,"offset":427,"style":"ITALIC"},{"length":15,"offset":472,"style":"ITALIC"},{"length":13,"offset":489,"style":"ITALIC"},{"length":44,"offset":526,"style":"ITALIC"},{"length":17,"offset":594,"style":"ITALIC"},{"length":10,"offset":613,"style":"ITALIC"},{"length":10,"offset":647,"style":"ITALIC"},{"length":12,"offset":683,"style":"ITALIC"},{"length":12,"offset":721,"style":"ITALIC"},{"length":20,"offset":735,"style":"ITALIC"},{"length":6,"offset":779,"style":"ITALIC"},{"length":6,"offset":809,"style":"ITALIC"},{"length":19,"offset":839,"style":"ITALIC"},{"length":13,"offset":860,"style":"ITALIC"},{"length":11,"offset":897,"style":"ITALIC"}],"text":"const str = \"JavaScript\";\n\n// Изменение регистра\nstr.toUpperCase(); // \"JAVASCRIPT\"\nstr.toLowerCase(); // \"javascript\"\n\n// Поиск\nstr.indexOf(\"Script\"); // 4\nstr.includes(\"Java\"); // true\nstr.startsWith(\"Java\"); // true\nstr.endsWith(\"pt\"); // true\n\n// Извлечение\nstr.slice(0, 4); // \"Java\"\nstr.substring(4, 10); // \"Script\"\nstr.substr(4, 6); // \"Script\" (устарел)\n\n// Замена\nstr.replace(\"Java\", \"Type\"); // \"TypeScript\"\nstr.replaceAll(\"a\", \"o\"); // \"JovoScript\"\n\n// Разделение\nstr.split(\"\"); // [\"J\",\"a\",\"v\",\"a\",\"S\",\"c\",\"r\",\"i\",\"p\",\"t\"]\nstr.split(\" \"); // [\"JavaScript\"]\n\n// Обрезка\n\" hello \".trim(); // \"hello\"\n\" hello \".trimStart(); // \"hello \"\n\" hello \".trimEnd(); // \" hello\"\n\n// Доступ по индексу\nstr[0]; // \"J\"\nstr.charAt(0); // \"J\"\nstr.charCodeAt(0); // 74 (код символа)\n\n// Повторение\n\"ha\".repeat(3); // \"hahaha\"","type":"unstyled","key":"b5l97"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 Числовые методы","type":"header-three","key":"mp1r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1ops7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":22,"style":"ITALIC"},{"length":21,"offset":76,"style":"ITALIC"},{"length":20,"offset":121,"style":"ITALIC"},{"length":26,"offset":143,"style":"ITALIC"},{"length":12,"offset":193,"style":"ITALIC"},{"length":47,"offset":207,"style":"ITALIC"},{"length":24,"offset":298,"style":"ITALIC"},{"length":27,"offset":346,"style":"ITALIC"},{"length":11,"offset":375,"style":"ITALIC"},{"length":7,"offset":410,"style":"ITALIC"},{"length":7,"offset":441,"style":"ITALIC"},{"length":7,"offset":472,"style":"ITALIC"},{"length":8,"offset":504,"style":"ITALIC"},{"length":12,"offset":514,"style":"ITALIC"},{"length":26,"offset":550,"style":"ITALIC"},{"length":9,"offset":600,"style":"ITALIC"},{"length":19,"offset":635,"style":"ITALIC"},{"length":24,"offset":678,"style":"ITALIC"}],"text":"const num = 123.456;\n\n// Округление и форматирование\nnum.toFixed(2); // \"123.46\" (строка!)\nnum.toPrecision(4); // \"123.5\" (строка!)\n\n// Экспоненциальная запись\nnum.toExponential(2); // \"1.23e+2\"\n\n// Преобразование в строку с системой счисления\nconst binary = 255;\nbinary.toString(2); // \"11111111\" (двоичная)\nbinary.toString(16); // \"ff\" (шестнадцатеричная)\n\n// Проверки\nNumber.isNaN(NaN); // true\nNumber.isFinite(42); // true\nNumber.isInteger(42); // true\nNumber.isInteger(42.5); // false\n\n// Константы\nNumber.MAX_VALUE; // 1.7976931348623157e+308\nNumber.MIN_VALUE; // 5e-324\nNumber.MAX_SAFE_INTEGER; // 9007199254740991\nNumber.EPSILON; // 2.220446049250313e-16","type":"unstyled","key":"d1olv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.3 Булевы методы","type":"header-three","key":"ft1ja"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6dvka"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":9,"offset":43,"style":"ITALIC"},{"length":7,"offset":76,"style":"ITALIC"},{"length":50,"offset":85,"style":"ITALIC"}],"text":"const bool = true;\n\nbool.toString(); // \"true\"\nbool.valueOf(); // true\n\n// У Boolean нет много методов, это просто обёртка","type":"unstyled","key":"151pl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Нюансы и подводные камни","type":"header-two","key":"bergt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.1 null и undefined не имеют обёрток","type":"header-three","key":"f3l9a"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"55kta"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":53,"offset":21,"style":"ITALIC"},{"length":58,"offset":97,"style":"ITALIC"}],"text":"null.toString(); // TypeError: Cannot read property 'toString' of null\nundefined.toString(); // TypeError: Cannot read property 'toString' of undefined","type":"unstyled","key":"2cnaf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.2 Числовые литералы и методы (осторожно с точкой)","type":"header-three","key":"9poud"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"a2ag2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":61,"offset":0,"style":"ITALIC"},{"length":37,"offset":78,"style":"ITALIC"},{"length":62,"offset":150,"style":"ITALIC"},{"length":30,"offset":213,"style":"ITALIC"}],"text":"// ❌ Ошибка (точка воспринимается как десятичный разделитель)\n42.toString();\n\n// ✅ Правильно (две точки или скобки)\n42..toString();\n(42).toString();\n\n// Почему так? Парсер видит \"42.\" как число с плавающей точкой\n// Вторая точка — вызов метода","type":"unstyled","key":"7b2ak"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.3 Примитивы и new","type":"header-three","key":"9bsnk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"15na1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":83,"style":"ITALIC"},{"length":11,"offset":121,"style":"ITALIC"},{"length":41,"offset":134,"style":"ITALIC"},{"length":8,"offset":213,"style":"ITALIC"},{"length":7,"offset":259,"style":"ITALIC"},{"length":33,"offset":268,"style":"ITALIC"},{"length":10,"offset":331,"style":"ITALIC"},{"length":48,"offset":372,"style":"ITALIC"}],"text":"const str1 = \"hello\";\nconst str2 = new String(\"hello\");\n\nconsole.log(typeof str1); // \"string\"\nconsole.log(typeof str2); // \"object\"\n\n// instanceof работает только с объектами\nconsole.log(str1 instanceof String); // false\nconsole.log(str2 instanceof String); // true\n\n// Но valueOf возвращает примитив\nconsole.log(str2.valueOf()); // \"hello\"\nconsole.log(str2 + \" world\"); // \"hello world\" (автоматическое преобразование)","type":"unstyled","key":"b8vrq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.4 Добавление методов в обёртки (никогда так не делайте!)","type":"header-three","key":"3i955"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cvsfi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":31,"offset":0,"style":"ITALIC"},{"length":10,"offset":152,"style":"ITALIC"},{"length":49,"offset":164,"style":"ITALIC"},{"length":49,"offset":214,"style":"ITALIC"},{"length":36,"offset":264,"style":"ITALIC"}],"text":"// Технически можно, но НЕ НАДО\nString.prototype.reverse = function() {\n return this.split('').reverse().join('');\n};\n\nconsole.log(\"hello\".reverse()); // \"olleh\"\n\n// Проблема: загрязнение глобального пространства\n// Потенциальные конфликты с будущими версиями JS\n// Другие библиотеки могут сломаться","type":"unstyled","key":"9dagc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Производительность: примитивы vs обёртки","type":"header-two","key":"e1llb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"edtdt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":0,"style":"ITALIC"},{"length":9,"offset":167,"style":"ITALIC"},{"length":45,"offset":326,"style":"ITALIC"}],"text":"// Тест производительности\nconsole.time(\"primitive\");\nfor (let i = 0; i < 10000000; i++) {\n const str = \"hello\";\n str.toUpperCase();\n}\nconsole.timeEnd(\"primitive\");\n// ~200ms\n\nconsole.time(\"wrapper\");\nfor (let i = 0; i < 10000000; i++) {\n const str = new String(\"hello\");\n str.toUpperCase();\n}\nconsole.timeEnd(\"wrapper\");\n// ~500ms (медленнее из-за создания объектов)","type":"unstyled","key":"3nvl4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Вывод: Всегда используйте примитивы. Обёртки нужны только движку внутри.","type":"unstyled","key":"arm7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Сравнение с другими языками","type":"header-two","key":"fcua5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Python","type":"header-three","key":"3f5jv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"python","type":"unstyled","key":"9rngg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":78,"offset":0,"style":"ITALIC"},{"length":9,"offset":96,"style":"ITALIC"},{"length":24,"offset":106,"style":"ITALIC"}],"text":"# Python: строки тоже имеют методы, но нет разницы между примитивом и объектом\n\"hello\".upper() # \"HELLO\"\n# В Python всё - объекты","type":"unstyled","key":"dnqnq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Java","type":"header-three","key":"e2961"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"java","type":"unstyled","key":"698oa"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":0,"style":"ITALIC"},{"length":24,"offset":47,"style":"ITALIC"},{"length":11,"offset":95,"style":"ITALIC"},{"length":31,"offset":130,"style":"ITALIC"},{"length":16,"offset":185,"style":"ITALIC"},{"length":11,"offset":225,"style":"ITALIC"}],"text":"// Java: явное различие\nString str = \"hello\"; // примитив? нет, объект\nint num = 42; // примитив\nnum.toString(); // Ошибка! int не имеет методов\nInteger wrapper = 42; // нужна обёртка\nwrapper.toString(); // работает","type":"unstyled","key":"5dg3t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"JavaScript - золотая середина","type":"header-three","key":"41mah"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"JavaScript берёт лучшее из двух миров: вы пишете как с примитивами (быстро), а работаете как с объектами (удобно).","type":"unstyled","key":"2elns"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Реальные примеры использования","type":"header-two","key":"crmi5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.1 Работа с датами","type":"header-three","key":"b48ok"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1f342"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":58,"style":"ITALIC"},{"length":9,"offset":113,"style":"ITALIC"}],"text":"const date = new Date();\nconsole.log(date.getFullYear()); // метод объекта Date\nconsole.log(date.toString()); // строка","type":"unstyled","key":"aot2c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.2 Регулярные выражения","type":"header-three","key":"56n7r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1g857"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":60,"style":"ITALIC"},{"length":4,"offset":109,"style":"ITALIC"},{"length":15,"offset":156,"style":"ITALIC"}],"text":"const str = \"JavaScript\";\nconsole.log(str.match(/[A-Z]/g)); // [\"J\", \"S\"]\nconsole.log(str.search(/Script/)); // 4\nconsole.log(str.replace(/Java/, \"Type\")); // \"TypeScript\"","type":"unstyled","key":"aqeu3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.3 Форматирование чисел","type":"header-three","key":"a3qhq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"b561f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":69,"style":"ITALIC"}],"text":"const price = 1234.5;\nconsole.log(`Цена: ${price.toFixed(2)} руб.`); // \"Цена: 1234.50 руб.\"","type":"unstyled","key":"bb13t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.4 Валидация строк","type":"header-three","key":"fca0b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2b5rs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"function isValidEmail(email) {\n return email.includes('@') && \n !email.startsWith('@') && \n email.lastIndexOf('.') > email.lastIndexOf('@');\n}","type":"unstyled","key":"8335u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Собственные методы для примитивов (полифилы)","type":"header-two","key":"338ut"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Хотя расширять встроенные прототипы - плохая практика, иногда нужно добавить поддержку современных методов в старые браузеры.","type":"unstyled","key":"ar6a8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2tkg5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":46,"offset":0,"style":"ITALIC"},{"length":28,"offset":238,"style":"ITALIC"},{"length":7,"offset":305,"style":"ITALIC"}],"text":"// Полифил для String.prototype.includes (ES6)\nif (!String.prototype.includes) {\n String.prototype.includes = function(search, start) {\n if (typeof start !== 'number') start = 0;\n return this.indexOf(search, start) !== -1;\n };\n}\n\n// Теперь работает даже в IE\nconsole.log(\"hello\".includes(\"ell\")); // true","type":"unstyled","key":"4l0ct"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Итоговая таблица","type":"header-two","key":"erbt5"},{"data":{"image":{"id":"69db56f53c4e4c67f97a1ed1"}},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"atomic:image","key":"d53a5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"bh2ca"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Манифест методов примитивов","type":"header-two","key":"6kb9u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":0,"style":"BOLD"}],"text":"Примитивы не имеют свойств - это иллюзия, создаваемая временными объектами-обёртками.","type":"ordered-list-item","key":"fgql2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":0,"style":"BOLD"}],"text":"Три основные обёртки: String, Number, Boolean.","type":"ordered-list-item","key":"bl968"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":0,"style":"BOLD"}],"text":"Не создавайте обёртки явно - используйте примитивы.","type":"ordered-list-item","key":"ccf93"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":36,"offset":0,"style":"BOLD"}],"text":"Временный объект живёт одну операцию - свойства, добавленные к нему, теряются.","type":"ordered-list-item","key":"efh8d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":3,"offset":4,"style":"BOLD"},{"length":17,"offset":16,"style":"BOLD"}],"text":"null и undefined не имеют обёрток - вызов метода приведёт к ошибке.","type":"ordered-list-item","key":"f41mh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":0,"style":"BOLD"}],"text":"Для чисел с точкой - используйте две точки или скобки.","type":"ordered-list-item","key":"mb78"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":0,"style":"BOLD"}],"text":"Булева обёртка всегда true - даже если внутри false.","type":"ordered-list-item","key":"d63qa"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":0,"style":"BOLD"}],"text":"Примитивы быстрее и безопаснее - всегда используйте их.","type":"ordered-list-item","key":"5i5c5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":0,"style":"BOLD"}],"text":"Финальный тест (что выведет?):","type":"unstyled","key":"57m7d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1q3hc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":138,"style":"ITALIC"}],"text":"const str = \"hello\";\nstr.test = \"world\";\nconsole.log(str.test);\n\nconst num = 10;\nconsole.log(num.toString());\nconsole.log(10.toString()); // Что здесь?\n\nconst bool = new Boolean(false);\nif (bool) {\n console.log(\"true or false?\");\n}\n\nconsole.log(typeof new Number(42));\nconsole.log(typeof 42);","type":"unstyled","key":"fm9hp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Ответ:","type":"unstyled","key":"av5l4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"undefined (свойство не сохранилось)","type":"unordered-list-item","key":"uh8s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"\"10\" (работает)","type":"unordered-list-item","key":"7k5jh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Ошибка синтаксиса (нужно 10..toString() или (10).toString())","type":"unordered-list-item","key":"7t426"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"\"true or false?\" (объект Boolean всегда true в if)","type":"unordered-list-item","key":"6080a"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"\"object\" (обёртка)","type":"unordered-list-item","key":"enf4b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"\"number\" (примитив)","type":"unordered-list-item","key":"8hon"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Методы примитивов - это элегантный компромисс между производительностью и удобством. JavaScript даёт вам скорость примитивов, но когда нужно - временно превращает их в объекты, наделяя всеми возможностями. Это как иметь друга, который умеет превращаться в супергероя ровно на секунду, чтобы помочь, а потом снова становится обычным человеком. Пользуйтесь этой силой, но помните о её временной природе.","type":"unstyled","key":"er8eg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------","type":"unstyled","key":"9del"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------","type":"unstyled","key":"5ct48"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Танцующие биты: Всё, что вы хотели знать о числах в JavaScript (но боялись спросить)","type":"header-two","key":"u9fl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"0.1 + 0.2 !== 0.3. Это знают даже те, кто никогда не писал ни строчки кода. Это визитная карточка JavaScript, его \"ахиллесова пята\" и одновременно урок смирения для всех, кто верит в математическую точность компьютеров.","type":"unstyled","key":"7puvc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Но за этой странностью скрывается целая вселенная: биты, экспоненты, специальные значения, грабли с округлением и неожиданные преобразования.","type":"unstyled","key":"aqa4n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Добро пожаловать в мир чисел JavaScript - места, где typeof NaN - \"number\", а деление на ноль не ломает программу, а возвращает бесконечность.","type":"unstyled","key":"1j97t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Один формат на всё: Number","type":"header-two","key":"bbi3s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":139,"style":"BOLD"}],"text":"В большинстве языков программирования есть отдельные типы для целых чисел (int) и чисел с плавающей точкой (float, double). В JavaScript - один-единственный тип number.","type":"unstyled","key":"a270o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"190fo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":25,"style":"ITALIC"},{"length":21,"offset":59,"style":"ITALIC"},{"length":16,"offset":107,"style":"ITALIC"},{"length":12,"offset":150,"style":"ITALIC"},{"length":26,"offset":189,"style":"ITALIC"},{"length":16,"offset":242,"style":"ITALIC"},{"length":20,"offset":285,"style":"ITALIC"}],"text":"const integer = 42; // целое\nconst float = 3.14; // с плавающей точкой\nconst negative = -10; // отрицательное\nconst scientific = 5e6; // 5 000 000\nconst hex = 0xFF; // 255 (шестнадцатеричная)\nconst binary = 0b1010; // 10 (двоичная)\nconst octal = 0o77; // 63 (восьмеричная)","type":"unstyled","key":"8ubn8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":58,"style":"BOLD"}],"text":"Все они — 64-битные числа с плавающей точкой по стандарту IEEE 754 (также известны как \"double precision\").","type":"unstyled","key":"9c0l4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. Как числа хранятся в памяти (IEEE 754)","type":"header-two","key":"1lt08"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Представьте, что у вас есть 64 бита (0 или 1) для хранения числа. Они распределены так:","type":"unstyled","key":"bg6a2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"text","type":"unstyled","key":"alqou"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"[знак][ экспонента ][ мантисса (дробная часть) ]\n[1 бит][ 11 битов ][ 52 бита ]","type":"unstyled","key":"bje0h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":0,"style":"BOLD"}],"text":"Знак (1 бит): 0 - положительное, 1 - отрицательное","type":"unordered-list-item","key":"ea8tl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":20,"offset":0,"style":"BOLD"}],"text":"Экспонента (11 бит): определяет порядок числа","type":"unordered-list-item","key":"1515o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":0,"style":"BOLD"}],"text":"Мантисса (52 бита): хранит значимые цифры","type":"unordered-list-item","key":"6l049"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":0,"style":"BOLD"}],"text":"Что это значит для нас?","type":"unstyled","key":"j0fu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Можно точно представить только числа вида n * 2^k","type":"unordered-list-item","key":"b0c13"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Десятичные дроби вроде 0.1 представляются приближённо","type":"unordered-list-item","key":"3v9jv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bq52k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":33,"offset":0,"style":"ITALIC"},{"length":22,"offset":58,"style":"ITALIC"},{"length":56,"offset":82,"style":"ITALIC"},{"length":46,"offset":139,"style":"ITALIC"},{"length":57,"offset":186,"style":"ITALIC"}],"text":"// Почему 0.1 + 0.2 не равно 0.3?\nconsole.log(0.1 + 0.2); // 0.30000000000000004\n\n// Потому что 0.1 в двоичной системе - бесконечная дробь\n// 0.1(10) = 0.0001100110011001100110011...(2)\n// Компьютер отрезает лишние биты, получается погрешность","type":"unstyled","key":"fmcqm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Специальные числовые значения","type":"header-two","key":"6o7em"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.1 NaN (Not a Number)","type":"header-three","key":"89tng"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"65mo9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":29,"style":"ITALIC"},{"length":6,"offset":68,"style":"ITALIC"},{"length":6,"offset":104,"style":"ITALIC"},{"length":17,"offset":112,"style":"ITALIC"},{"length":34,"offset":159,"style":"ITALIC"},{"length":8,"offset":223,"style":"ITALIC"},{"length":23,"offset":233,"style":"ITALIC"},{"length":23,"offset":287,"style":"ITALIC"},{"length":40,"offset":341,"style":"ITALIC"},{"length":19,"offset":420,"style":"ITALIC"},{"length":17,"offset":478,"style":"ITALIC"}],"text":"console.log(0 / 0); // NaN\nconsole.log(parseInt(\"hello\")); // NaN\nconsole.log(Math.sqrt(-1)); // NaN\n\n// Странности NaN\nconsole.log(NaN === NaN); // false (даже сам себе не равен!)\nconsole.log(NaN == NaN); // false\n\n// Как проверить на NaN\nconsole.log(isNaN(NaN)); // true (но есть нюанс)\nconsole.log(isNaN(\"hello\")); // true (сначала приводит к числу → NaN)\nconsole.log(Number.isNaN(NaN)); // true (безопасно)\nconsole.log(Number.isNaN(\"hello\")); // false (строго)","type":"unstyled","key":"c44u4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.2 Infinity и -Infinity","type":"header-three","key":"dj65i"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7e7qu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":29,"style":"ITALIC"},{"length":12,"offset":70,"style":"ITALIC"},{"length":11,"offset":118,"style":"ITALIC"},{"length":12,"offset":131,"style":"ITALIC"},{"length":7,"offset":178,"style":"ITALIC"},{"length":7,"offset":222,"style":"ITALIC"},{"length":28,"offset":231,"style":"ITALIC"},{"length":11,"offset":291,"style":"ITALIC"},{"length":6,"offset":337,"style":"ITALIC"}],"text":"console.log(1 / 0); // Infinity\nconsole.log(-1 / 0); // -Infinity\nconsole.log(Number.MAX_VALUE * 2); // Infinity\n\n// Сравнение\nconsole.log(Infinity > 1000000); // true\nconsole.log(Infinity === Infinity); // true\n\n// Операции с бесконечностью\nconsole.log(Infinity + 1000); // Infinity\nconsole.log(Infinity / Infinity); // NaN","type":"unstyled","key":"7tfs7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.3 -0 (Отрицательный ноль)","type":"header-three","key":"dib6p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7elmh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":94,"style":"ITALIC"},{"length":11,"offset":152,"style":"ITALIC"},{"length":12,"offset":196,"style":"ITALIC"},{"length":33,"offset":210,"style":"ITALIC"},{"length":8,"offset":276,"style":"ITALIC"}],"text":"const positiveZero = 0;\nconst negativeZero = -0;\n\nconsole.log(positiveZero === negativeZero); // true (формально равны)\nconsole.log(1 / positiveZero); // Infinity\nconsole.log(1 / negativeZero); // -Infinity\n\n// Отличить можно через Object.is\nconsole.log(Object.is(0, -0)); // false","type":"unstyled","key":"qcol"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":15,"offset":0,"style":"BOLD"}],"text":"Зачем нужен -0? Для математических операций, где важно направление (например, в анимациях и физике).","type":"unstyled","key":"p4lo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Безопасные целые числа","type":"header-two","key":"2eutv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Из-за формата хранения не все целые числа можно представить точно.","type":"unstyled","key":"ariav"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"76hf5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":38,"style":"ITALIC"},{"length":20,"offset":107,"style":"ITALIC"},{"length":31,"offset":171,"style":"ITALIC"},{"length":30,"offset":245,"style":"ITALIC"},{"length":33,"offset":276,"style":"ITALIC"},{"length":24,"offset":311,"style":"ITALIC"},{"length":7,"offset":389,"style":"ITALIC"},{"length":8,"offset":450,"style":"ITALIC"}],"text":"console.log(Number.MAX_SAFE_INTEGER); // 9007199254740991 (2^53 - 1)\nconsole.log(Number.MIN_SAFE_INTEGER); // -9007199254740991\n\nconsole.log(Number.MAX_SAFE_INTEGER + 1); // 9007199254740992 (ещё точно)\nconsole.log(Number.MAX_SAFE_INTEGER + 2); // 9007199254740992 (уже нет!)\n// Оба дают одинаковый результат!\n\n// Проверка безопасности\nconsole.log(Number.isSafeInteger(9007199254740991)); // true\nconsole.log(Number.isSafeInteger(9007199254740992)); // false","type":"unstyled","key":"952lc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. BigInt: Спасение для больших чисел","type":"header-two","key":"207tv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Когда чисел Number перестаёт хватать, на сцену выходит BigInt.","type":"unstyled","key":"emp2k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"5137h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":40,"style":"ITALIC"},{"length":11,"offset":143,"style":"ITALIC"},{"length":20,"offset":185,"style":"ITALIC"},{"length":21,"offset":236,"style":"ITALIC"},{"length":47,"offset":259,"style":"ITALIC"},{"length":43,"offset":307,"style":"ITALIC"},{"length":17,"offset":352,"style":"ITALIC"},{"length":28,"offset":401,"style":"ITALIC"},{"length":20,"offset":461,"style":"ITALIC"},{"length":21,"offset":483,"style":"ITALIC"},{"length":7,"offset":536,"style":"ITALIC"},{"length":19,"offset":582,"style":"ITALIC"},{"length":7,"offset":642,"style":"ITALIC"}],"text":"const big = 9007199254740991n; // суффикс n\nconst alsoBig = BigInt(9007199254740991);\nconst huge = BigInt(\"9999999999999999999999\");\n\n// Операции\nconsole.log(big + 1n); // 9007199254740992n\nconsole.log(big * 2n); // 18014398509481982n\n\n// Нельзя смешивать с Number без преобразования\n// console.log(big + 5); // TypeError!\n\n// Преобразование\nconsole.log(Number(big)); // рискуете потерей точности\nconsole.log(String(big)); // строка без потерь\n\n// Сравнение работает\nconsole.log(big > 100); // true\nconsole.log(big == 9007199254740991); // true (нестрогое)\nconsole.log(big === 9007199254740991n); // true","type":"unstyled","key":"abq8u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Методы чисел: Полный арсенал","type":"header-two","key":"3ij8b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 Преобразование в строку","type":"header-three","key":"f947s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2f1ch"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":45,"style":"ITALIC"},{"length":33,"offset":81,"style":"ITALIC"},{"length":30,"offset":138,"style":"ITALIC"},{"length":33,"offset":192,"style":"ITALIC"},{"length":17,"offset":227,"style":"ITALIC"},{"length":43,"offset":268,"style":"ITALIC"},{"length":35,"offset":335,"style":"ITALIC"},{"length":13,"offset":394,"style":"ITALIC"}],"text":"const num = 123.456;\n\nnum.toString(); // \"123.456\"\nnum.toString(2); // \"1111011.011101...\" (двоичная)\nnum.toString(8); // \"173.351...\" (восьмеричная)\nnum.toString(16); // \"7b.74...\" (шестнадцатеричная)\n\n// Форматирование\nnum.toFixed(2); // \"123.46\" (округляет, возвращает строку!)\nnum.toPrecision(4); // \"123.5\" (всего 4 значащих цифры)\nnum.toExponential(3); // \"1.235e+2\"","type":"unstyled","key":"cinng"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 Проверки","type":"header-three","key":"36agj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7hbs3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":27,"style":"ITALIC"},{"length":7,"offset":62,"style":"ITALIC"},{"length":8,"offset":97,"style":"ITALIC"},{"length":7,"offset":133,"style":"ITALIC"},{"length":8,"offset":168,"style":"ITALIC"},{"length":7,"offset":204,"style":"ITALIC"}],"text":"Number.isNaN(NaN); // true\nNumber.isFinite(42); // true\nNumber.isFinite(Infinity); // false\nNumber.isInteger(42); // true\nNumber.isInteger(42.5); // false\nNumber.isSafeInteger(42); // true","type":"unstyled","key":"c43u5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.3 Константы","type":"header-three","key":"77rmj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4s73n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":27,"style":"ITALIC"},{"length":37,"offset":81,"style":"ITALIC"},{"length":19,"offset":146,"style":"ITALIC"},{"length":20,"offset":193,"style":"ITALIC"},{"length":35,"offset":241,"style":"ITALIC"},{"length":11,"offset":304,"style":"ITALIC"},{"length":12,"offset":343,"style":"ITALIC"}],"text":"Number.MAX_VALUE; // 1.7976931348623157e+308\nNumber.MIN_VALUE; // 5e-324 (минимальное положительное)\nNumber.MAX_SAFE_INTEGER; // 9007199254740991\nNumber.MIN_SAFE_INTEGER; // -9007199254740991\nNumber.EPSILON; // 2.220446049250313e-16 (точность)\nNumber.POSITIVE_INFINITY; // Infinity\nNumber.NEGATIVE_INFINITY; // -Infinity","type":"unstyled","key":"4qap4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Арифметика с подвохом","type":"header-two","key":"2ic1k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.1 Проблема точности и её решение","type":"header-three","key":"6cajg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"r1h8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":0,"style":"ITALIC"},{"length":8,"offset":31,"style":"ITALIC"},{"length":25,"offset":41,"style":"ITALIC"},{"length":7,"offset":196,"style":"ITALIC"},{"length":37,"offset":205,"style":"ITALIC"},{"length":7,"offset":279,"style":"ITALIC"},{"length":53,"offset":288,"style":"ITALIC"},{"length":7,"offset":387,"style":"ITALIC"}],"text":"// Классика\n0.1 + 0.2 === 0.3; // false\n\n// Решение 1: погрешность\nfunction areEqual(a, b, epsilon = Number.EPSILON) {\n return Math.abs(a - b) < epsilon;\n}\nconsole.log(areEqual(0.1 + 0.2, 0.3)); // true\n\n// Решение 2: работа с целыми числами\n(0.1 * 10 + 0.2 * 10) / 10 === 0.3; // true\n\n// Решение 3: toFixed (осторожно — возвращает строку)\nparseFloat((0.1 + 0.2).toFixed(10)) === 0.3; // true","type":"unstyled","key":"37bf4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.2 Погрешность накапливается","type":"header-three","key":"3dqn6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fg853"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":78,"style":"ITALIC"},{"length":8,"offset":131,"style":"ITALIC"}],"text":"let sum = 0;\nfor (let i = 0; i < 10; i++) {\n sum += 0.1;\n}\nconsole.log(sum); // 0.9999999999999999 (не 1)\nconsole.log(sum === 1); // false","type":"unstyled","key":"cf84c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.3 Неожиданные результаты","type":"header-three","key":"69p1a"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6las1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":26,"style":"ITALIC"},{"length":21,"offset":75,"style":"ITALIC"},{"length":21,"offset":123,"style":"ITALIC"},{"length":27,"offset":146,"style":"ITALIC"},{"length":14,"offset":200,"style":"ITALIC"},{"length":15,"offset":243,"style":"ITALIC"}],"text":"console.log(0.1 + 0.2); // 0.30000000000000004\nconsole.log(0.1 + 0.7); // 0.7999999999999999\nconsole.log(0.2 + 0.4); // 0.6000000000000001\n\n// Есть и точные комбинации\nconsole.log(0.25 + 0.25); // 0.5 (точно)\nconsole.log(0.125 + 0.125); // 0.25 (точно)","type":"unstyled","key":"fk3m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Преобразование в число","type":"header-two","key":"4uovc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.1 Явное преобразование","type":"header-three","key":"9lfvj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"p751"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":22,"style":"ITALIC"},{"length":6,"offset":51,"style":"ITALIC"},{"length":6,"offset":80,"style":"ITALIC"},{"length":4,"offset":109,"style":"ITALIC"},{"length":4,"offset":136,"style":"ITALIC"},{"length":4,"offset":163,"style":"ITALIC"},{"length":6,"offset":190,"style":"ITALIC"},{"length":25,"offset":198,"style":"ITALIC"},{"length":6,"offset":246,"style":"ITALIC"},{"length":4,"offset":275,"style":"ITALIC"},{"length":24,"offset":281,"style":"ITALIC"},{"length":6,"offset":328,"style":"ITALIC"},{"length":16,"offset":357,"style":"ITALIC"},{"length":7,"offset":396,"style":"ITALIC"},{"length":23,"offset":405,"style":"ITALIC"},{"length":25,"offset":451,"style":"ITALIC"},{"length":41,"offset":499,"style":"ITALIC"},{"length":31,"offset":541,"style":"ITALIC"},{"length":4,"offset":595,"style":"ITALIC"}],"text":"Number(\"123\"); // 123\nNumber(\"123abc\"); // NaN\nNumber(\" 123 \"); // 123\nNumber(true); // 1\nNumber(false); // 0\nNumber(null); // 0\nNumber(undefined); // NaN\n\n// Унарный плюс (быстрее)\n+\"123\"; // 123\n+true; // 1\n\n// parseInt и parseFloat\nparseInt(\"123px\"); // 123\nparseInt(\"1010\", 2); // 10 (двоичная)\nparseFloat(\"3.14cm\"); // 3.14\n\n// Осторожно с parseInt\nparseInt(\"0x10\"); // 16 (шестнадцатеричная)\nparseInt(\"08\"); // 8 (но в старых браузерах могло быть 0)\n// Всегда указывайте основание:\nparseInt(\"08\", 10); // 8","type":"unstyled","key":"1hlol"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.2 Неявное преобразование","type":"header-three","key":"d4gd7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"i10d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":24,"offset":14,"style":"ITALIC"},{"length":5,"offset":53,"style":"ITALIC"},{"length":6,"offset":73,"style":"ITALIC"},{"length":6,"offset":94,"style":"ITALIC"},{"length":19,"offset":102,"style":"ITALIC"},{"length":32,"offset":136,"style":"ITALIC"}],"text":"\"5\" - 3; // 2 (минус любит числа)\n\"5\" * \"2\"; // 10\n\"5\" / \"2\"; // 2.5\n\"hello\" - 1; // NaN\n\n// Плюс — особенный\n\"5\" + 3; // \"53\" (строковая конкатенация)","type":"unstyled","key":"10jlf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Округление: Тонкости и подводные камни","type":"header-two","key":"9pc95"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dhajq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":42,"style":"ITALIC"},{"length":12,"offset":74,"style":"ITALIC"},{"length":20,"offset":107,"style":"ITALIC"},{"length":32,"offset":148,"style":"ITALIC"},{"length":19,"offset":182,"style":"ITALIC"},{"length":4,"offset":222,"style":"ITALIC"},{"length":52,"offset":247,"style":"ITALIC"},{"length":27,"offset":301,"style":"ITALIC"},{"length":19,"offset":351,"style":"ITALIC"},{"length":15,"offset":405,"style":"ITALIC"}],"text":"const num = 3.14159;\n\nMath.floor(num); // 3 (вниз)\nMath.ceil(num); // 4 (вверх)\nMath.round(num); // 3 (до ближайшего)\nMath.trunc(num); // 3 (отбрасывает дробную часть)\n\n// Проблема с round\nMath.round(1.5); // 2\nMath.round(-1.5); // -1 (а не -2! округляет к ближайшему целому вверх)\n\n// Форматирование с toFixed\n(3.14159).toFixed(2); // \"3.14\" (строка!)\nparseFloat((3.14159).toFixed(2)); // 3.14 (число)","type":"unstyled","key":"d1s79"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Работа с большими числами","type":"header-two","key":"3juse"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6dpiv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":36,"offset":0,"style":"ITALIC"},{"length":11,"offset":81,"style":"ITALIC"},{"length":27,"offset":94,"style":"ITALIC"},{"length":19,"offset":291,"style":"ITALIC"},{"length":36,"offset":338,"style":"ITALIC"}],"text":"// Проблема с очень большими числами\nconst huge = 1e308;\nconsole.log(huge * 2); // Infinity\n\n// Проверка на переполнение\nfunction safeMultiply(a, b) {\n const result = a * b;\n if (result === Infinity || result === -Infinity) {\n throw new Error(\"Переполнение!\");\n }\n return result;\n}\n\n// Решение с BigInt\nconst big1 = 10n ** 100n; // 10 в степени 100 (огромное число)\nconst big2 = 123456789012345678901234567890n;","type":"unstyled","key":"34fmq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Полезные трюки","type":"header-two","key":"f9m3l"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.1 Быстрое округление (побитовые операторы)","type":"header-three","key":"10sm9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"689j7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":17,"offset":45,"style":"ITALIC"},{"length":18,"offset":90,"style":"ITALIC"},{"length":12,"offset":136,"style":"ITALIC"},{"length":50,"offset":150,"style":"ITALIC"},{"length":29,"offset":228,"style":"ITALIC"}],"text":"const num = 3.14;\nconsole.log(~~num); // 3 (двойное НЕ)\nconsole.log(num | 0); // 3 (битовое ИЛИ)\nconsole.log(num >> 0); // 3 (сдвиг)\n\n// Внимание: работают только с 32-битными числами!\nconsole.log(~~2147483648); // -2147483648 (переполнение)","type":"unstyled","key":"cf5uj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.2 Проверка, является ли число целым","type":"header-three","key":"83jsi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8mmdb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":83,"style":"ITALIC"},{"length":8,"offset":121,"style":"ITALIC"},{"length":21,"offset":165,"style":"ITALIC"}],"text":"function isInteger(num) {\n return num % 1 === 0;\n}\n\nconsole.log(isInteger(42)); // true\nconsole.log(isInteger(42.5)); // false\nconsole.log(Number.isInteger(42)); // современный способ","type":"unstyled","key":"32osq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.3 Генерация случайного числа в диапазоне","type":"header-three","key":"4if4f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3l9am"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":200,"style":"ITALIC"},{"length":23,"offset":250,"style":"ITALIC"}],"text":"function random(min, max) {\n return Math.random() * (max - min) + min;\n}\n\nfunction randomInt(min, max) {\n return Math.floor(Math.random() * (max - min + 1)) + min;\n}\n\nconsole.log(random(5, 10)); // 5..10 (дробное)\nconsole.log(randomInt(5, 10)); // 5,6,7,8,9,10 (целое)","type":"unstyled","key":"6dc1u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.4 Суммирование с защитой от погрешностей","type":"header-three","key":"a9uof"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"5da8j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":184,"style":"ITALIC"}],"text":"function sumSafe(...nums) {\n let total = 0;\n for (const num of nums) {\n total = parseFloat((total + num).toFixed(10));\n }\n return total;\n}\n\nconsole.log(sumSafe(0.1, 0.2, 0.3)); // 0.6 (не 0.6000000000000001)","type":"unstyled","key":"fmjnk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Подводные камни (обязательно к прочтению!)","type":"header-two","key":"cqka0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #1: typeof NaN === \"number\"","type":"header-three","key":"5f7qs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fep34"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":25,"style":"ITALIC"}],"text":"console.log(typeof NaN); // \"number\" (самый коварный баг)","type":"unstyled","key":"8bldk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #2: Math.max() и Math.min() без аргументов","type":"header-three","key":"v42c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2j8d9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":25,"style":"ITALIC"},{"length":11,"offset":63,"style":"ITALIC"},{"length":24,"offset":113,"style":"ITALIC"}],"text":"console.log(Math.max()); // -Infinity\nconsole.log(Math.min()); // Infinity\nconsole.log(Math.max() > Math.min()); // true (да, так бывает)","type":"unstyled","key":"e9m8p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #3: Сравнение NaN","type":"header-three","key":"601ov"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3utfb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":45,"style":"ITALIC"},{"length":12,"offset":143,"style":"ITALIC"}],"text":"const result = 0 / 0;\nif (result === NaN) { // никогда не сработает\n console.log(\"NaN\");\n}\nif (Number.isNaN(result)) {\n console.log(\"NaN\"); // правильно\n}","type":"unstyled","key":"2ft16"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #4: Потеря точности при больших целых","type":"header-three","key":"2ev51"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1lbq0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":35,"offset":31,"style":"ITALIC"}],"text":"console.log(9999999999999999); // 10000000000000000 (округлилось!)","type":"unstyled","key":"6g922"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #5: toFixed возвращает строку","type":"header-three","key":"7ahk2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4blio"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":54,"style":"ITALIC"},{"length":26,"offset":101,"style":"ITALIC"},{"length":51,"offset":128,"style":"ITALIC"}],"text":"const price = 9.99;\nconst rounded = price.toFixed(1); // \"10.0\" (строка!)\nconst total = rounded + 5; // \"10.05\" (конкатенация!)\n// Всегда преобразуйте обратно: parseFloat(rounded)","type":"unstyled","key":"85lkv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 13. Реальные кейсы","type":"header-two","key":"3da71"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.1 Финансовые расчёты","type":"header-three","key":"5drod"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"c7ril"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":29,"offset":0,"style":"ITALIC"},{"length":22,"offset":125,"style":"ITALIC"},{"length":43,"offset":291,"style":"ITALIC"}],"text":"// Плохо (с плавающей точкой)\nfunction calculateTotal(items) {\n return items.reduce((sum, item) => sum + item.price, 0);\n}\n\n// Хорошо (в копейках)\nfunction calculateTotalSafe(items) {\n const totalCents = items.reduce((sum, item) => sum + item.priceCents, 0);\n return totalCents / 100;\n}\n\n// Или с использованием BigInt для точности\nfunction calculateTotalBigInt(items) {\n const totalCents = items.reduce(\n (sum, item) => sum + BigInt(item.priceCents), \n 0n\n );\n return Number(totalCents) / 100;\n}","type":"unstyled","key":"8n5bk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.2 Проверка на целое число","type":"header-three","key":"bd3gt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"47qi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":128,"style":"ITALIC"},{"length":8,"offset":173,"style":"ITALIC"},{"length":8,"offset":220,"style":"ITALIC"},{"length":8,"offset":266,"style":"ITALIC"}],"text":"function isIntegerSafe(num) {\n return Number.isFinite(num) && Math.floor(num) === num;\n}\n\nconsole.log(isIntegerSafe(42)); // true\nconsole.log(isIntegerSafe(42.5)); // false\nconsole.log(isIntegerSafe(Infinity)); // false\nconsole.log(isIntegerSafe(NaN)); // false","type":"unstyled","key":"cgv9g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.3 Сравнение с погрешностью","type":"header-three","key":"8gum0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fph9t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":142,"style":"ITALIC"}],"text":"function numbersEqual(a, b, tolerance = Number.EPSILON) {\n return Math.abs(a - b) < tolerance;\n}\n\nconsole.log(numbersEqual(0.1 + 0.2, 0.3)); // true","type":"unstyled","key":"d7vdd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Манифест чисел","type":"header-two","key":"3h1oi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":0,"style":"BOLD"}],"text":"Все числа - 64-битные float - нет отдельного типа для целых.","type":"ordered-list-item","key":"4da53"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"0.1 + 0.2 !== 0.3 - из-за двоичного представления. Используйте погрешность.","type":"ordered-list-item","key":"3hvpq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":3,"style":"BOLD"}],"text":"NaN не равен сам себе - проверяйте через Number.isNaN().","type":"ordered-list-item","key":"6inl0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":3,"offset":8,"style":"BOLD"}],"text":"Infinity и -Infinity - результат деления на ноль.","type":"ordered-list-item","key":"525oe"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"BigInt - для целых чисел больше 2^53 - 1.","type":"ordered-list-item","key":"7233e"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":7,"style":"BOLD"}],"text":"toFixed возвращает строку - не забывайте преобразовывать обратно.","type":"ordered-list-item","key":"bi4ht"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":0,"style":"BOLD"}],"text":"Для финансов - работайте в копейках/центах (целых числах) или используйте BigInt.","type":"ordered-list-item","key":"7r8g1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":0,"style":"BOLD"}],"text":"Финальный тест (проверьте себя):","type":"unstyled","key":"bbpn2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"f7qpg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"console.log(0.1 + 0.2 === 0.3);\nconsole.log(NaN === NaN);\nconsole.log(Number.isNaN(NaN));\nconsole.log(1 / 0);\nconsole.log(parseInt(\"08\"));\nconsole.log(Number.MAX_SAFE_INTEGER + 1 === Number.MAX_SAFE_INTEGER + 2);\nconsole.log(typeof NaN);\nconsole.log(0.1 + 0.7 === 0.8);","type":"unstyled","key":"es6dn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":0,"style":"BOLD"}],"text":"Ответы: false, false, true, Infinity, 8 (с указанием основания 10), true (потеря точности), \"number\", false.","type":"unstyled","key":"ancbn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Числа в JavaScript - это одновременно и сила, и слабость языка. С одной стороны, простота (один тип на всё). С другой - необходимость помнить о погрешностях, безопасных диапазонах и специальных значениях. Но когда вы понимаете эти особенности, перестаёте бояться 0.1 + 0.2 и начинаете использовать числа в полной их мощи. Считайте с удовольствием!","type":"unstyled","key":"2uh84"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"elpvk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------------","type":"unstyled","key":"8klt9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------------","type":"unstyled","key":"58hsk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Искусство управления текстом: Полное руководство по строкам в JavaScript","type":"header-two","key":"2o5v5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Строки - это, пожалуй, самый частый гость в вашем коде. Имена пользователей, сообщения в чате, JSON-ответы от сервера, URL-адреса, CSS-классы - всё это строки. Мы работаем с ними каждый день, но часто используем лишь малую часть их возможностей.","type":"unstyled","key":"5k2h9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Строки в JavaScript - это не просто последовательности символов. Это неизменяемые, умные, богатые методами структуры, которые умеют искать, заменять, резать, склеивать и даже выполнять регулярные выражения.","type":"unstyled","key":"fmg69"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Сегодня мы погрузимся в мир строк от основ до продвинутых техник.","type":"unstyled","key":"c44qi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Что такое строка в JavaScript?","type":"header-two","key":"dbmaa"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Строка - это последовательность символов (букв, цифр, знаков препинания, эмодзи). В JavaScript строки представлены в кодировке UTF-16, что позволяет работать с любыми символами Юникода.","type":"unstyled","key":"1spk6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1931f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":38,"style":"ITALIC"},{"length":20,"offset":95,"style":"ITALIC"},{"length":25,"offset":154,"style":"ITALIC"}],"text":"const str1 = \"Привет, мир!\"; // двойные кавычки\nconst str2 = 'Hello, world!'; // одинарные кавычки\nconst str3 = `Шаблонная строка`; // обратные кавычки (ES6)","type":"unstyled","key":"dd62d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Важно: Строки неизменяемы (immutable). Вы не можете изменить отдельный символ существующей строки.","type":"unstyled","key":"3o913"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3vrqr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":51,"style":"ITALIC"},{"length":45,"offset":80,"style":"ITALIC"},{"length":10,"offset":170,"style":"ITALIC"}],"text":"let str = \"hello\";\nstr[0] = \"H\";\nconsole.log(str); // \"hello\" (не изменилось!)\n\n// Чтобы изменить, нужно создать новую строку\nstr = \"H\" + str.slice(1);\nconsole.log(str); // \"Hello\"","type":"unstyled","key":"ckact"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. Три способа создать строку (и когда какой использовать)","type":"header-two","key":"cuuh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.1 Одинарные и двойные кавычки - полные близнецы","type":"header-three","key":"eloge"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"efpsm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":34,"offset":71,"style":"ITALIC"},{"length":16,"offset":206,"style":"ITALIC"}],"text":"const single = 'Одинарные кавычки';\nconst double = \"Двойные кавычки\";\n\n// Разницы нет, выбирайте по вкусу\nconst withDoubleInside = \"Он сказал: 'Привет'\";\nconst withSingleInside = 'Она ответила: \"Привет\"';\n\n// Экранирование\nconst quote = 'Он сказал: \\'Привет\\'';\nconst backslash = \"Путь к файлу: C:\\\\Users\\\\Name\";","type":"unstyled","key":"e912f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.2 Шаблонные строки (обратные кавычки) - современный стандарт","type":"header-three","key":"41jc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dp58s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":38,"style":"ITALIC"},{"length":31,"offset":142,"style":"ITALIC"},{"length":28,"offset":175,"style":"ITALIC"},{"length":23,"offset":276,"style":"ITALIC"},{"length":14,"offset":335,"style":"ITALIC"}],"text":"const name = \"Анна\";\nconst age = 25;\n\n// Интерполяция переменных\nconst greeting = `Привет, ${name}! Тебе ${age} лет.`;\nconsole.log(greeting); // \"Привет, Анна! Тебе 25 лет.\"\n\n// Многострочность (без \\n!)\nconst multiline = `\n Первая строка\n Вторая строка\n Третья строка\n`;\n\n// Выражения внутри ${}\nconst total = `Сумма: ${10 + 20}`; // \"Сумма: 30\"\nconst condition = `Статус: ${age >= 18 ? \"взрослый\" : \"ребёнок\"}`;","type":"unstyled","key":"c3io6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Свойства и методы строк","type":"header-two","key":"43nik"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.1 length - длина строки","type":"header-three","key":"83ov6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"191dr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":5,"offset":51,"style":"ITALIC"},{"length":35,"offset":58,"style":"ITALIC"},{"length":28,"offset":140,"style":"ITALIC"}],"text":"const str = \"JavaScript\";\nconsole.log(str.length); // 10\n\n// Эмодзи считаются как один символ\nconst emoji = \"\uD83D\uDE0A\";\nconsole.log(emoji.length); // 1 (в современных движках)","type":"unstyled","key":"et1jq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.2 Доступ к символам","type":"header-three","key":"9rkbe"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7a7ui"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":36,"offset":22,"style":"ITALIC"},{"length":6,"offset":80,"style":"ITALIC"},{"length":6,"offset":108,"style":"ITALIC"},{"length":12,"offset":137,"style":"ITALIC"},{"length":31,"offset":151,"style":"ITALIC"},{"length":6,"offset":211,"style":"ITALIC"},{"length":21,"offset":247,"style":"ITALIC"},{"length":36,"offset":270,"style":"ITALIC"},{"length":15,"offset":339,"style":"ITALIC"},{"length":27,"offset":400,"style":"ITALIC"}],"text":"const str = \"Hello\";\n\n// Квадратные скобки (только чтение)\nconsole.log(str[0]); // \"H\"\nconsole.log(str[4]); // \"o\"\nconsole.log(str[10]); // undefined\n\n// charAt (более старый способ)\nconsole.log(str.charAt(0)); // \"H\"\nconsole.log(str.charAt(10)); // \"\" (пустая строка)\n\n// charCodeAt — код символа (UTF-16)\nconsole.log(str.charCodeAt(0)); // 72 (код 'H')\nconsole.log(str.charCodeAt(0).toString(16)); // \"48\" (шестнадцатеричный)","type":"unstyled","key":"3vj3h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.3 Итерация по строке","type":"header-three","key":"f2vdv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"u3hh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":41,"offset":23,"style":"ITALIC"},{"length":19,"offset":114,"style":"ITALIC"},{"length":42,"offset":135,"style":"ITALIC"}],"text":"const str = \"Привет\";\n\n// for...of (работает с эмодзи правильно)\nfor (const char of str) {\n console.log(char);\n}\n// П, р, и, в, е, т\n\n// for (старый способ, ломается на эмодзи)\nfor (let i = 0; i < str.length; i++) {\n console.log(str[i]);\n}","type":"unstyled","key":"9pt5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Основные методы работы со строками","type":"header-two","key":"e6s69"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.1 Поиск в строке","type":"header-three","key":"4pilv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"a5i2s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":37,"offset":47,"style":"ITALIC"},{"length":5,"offset":128,"style":"ITALIC"},{"length":18,"offset":177,"style":"ITALIC"},{"length":44,"offset":197,"style":"ITALIC"},{"length":5,"offset":277,"style":"ITALIC"},{"length":31,"offset":284,"style":"ITALIC"},{"length":7,"offset":355,"style":"ITALIC"},{"length":8,"offset":402,"style":"ITALIC"},{"length":14,"offset":451,"style":"ITALIC"},{"length":24,"offset":467,"style":"ITALIC"},{"length":7,"offset":531,"style":"ITALIC"},{"length":8,"offset":578,"style":"ITALIC"},{"length":7,"offset":626,"style":"ITALIC"}],"text":"const str = \"JavaScript - замечательный язык\";\n// indexOf - индекс первого вхождения\nconsole.log(str.indexOf(\"замечательный\")); // 11\nconsole.log(str.indexOf(\"Python\")); // -1 (не найдено)\n\n// lastIndexOf - индекс последнего вхождения\nconsole.log(str.lastIndexOf(\"а\")); // 18\n\n// includes - проверяет наличие\nconsole.log(str.includes(\"Java\")); // true\nconsole.log(str.includes(\"Python\")); // false\nconsole.log(str.includes(\"скрипт\", 5)); // с позиции 5\n\n// startsWith / endsWith\nconsole.log(str.startsWith(\"Java\")); // true\nconsole.log(str.startsWith(\"Script\")); // false\nconsole.log(str.endsWith(\"язык\")); // true","type":"unstyled","key":"41kgr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.2 Извлечение частей строки","type":"header-three","key":"460h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fac3v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":45,"offset":38,"style":"ITALIC"},{"length":15,"offset":118,"style":"ITALIC"},{"length":12,"offset":168,"style":"ITALIC"},{"length":11,"offset":215,"style":"ITALIC"},{"length":44,"offset":228,"style":"ITALIC"},{"length":15,"offset":308,"style":"ITALIC"},{"length":46,"offset":359,"style":"ITALIC"},{"length":38,"offset":407,"style":"ITALIC"},{"length":26,"offset":477,"style":"ITALIC"}],"text":"const str = \"JavaScript is awesome\";\n\n// slice (поддерживает отрицательные индексы)\nconsole.log(str.slice(0, 10)); // \"JavaScript\"\nconsole.log(str.slice(-7)); // \"awesome\"\nconsole.log(str.slice(-7, -1)); // \"awesom\"\n\n// substring (не поддерживает отрицательные)\nconsole.log(str.substring(0, 10)); // \"JavaScript\"\nconsole.log(str.substring(-7)); // \"JavaScript is awesome\" (отрицательное → 0)\n\n// substr (устаревший, не используйте)\nconsole.log(str.substr(4, 6)); // \"Script\" (с 4, длина 6)","type":"unstyled","key":"d5598"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.3 Регистр символов","type":"header-three","key":"7srho"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"asid6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":15,"offset":59,"style":"ITALIC"},{"length":15,"offset":107,"style":"ITALIC"},{"length":43,"offset":124,"style":"ITALIC"},{"length":31,"offset":245,"style":"ITALIC"}],"text":"const str = \"JavaScript\";\n\nconsole.log(str.toUpperCase()); // \"JAVASCRIPT\"\nconsole.log(str.toLowerCase()); // \"javascript\"\n\n// toLocaleUpperCase для специфичных языков\nconst turkish = \"İstanbul\";\nconsole.log(turkish.toLocaleLowerCase('tr-TR')); // \"istanbul\" (без точки над i)","type":"unstyled","key":"56a9t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.4 Обрезка пробелов","type":"header-three","key":"f1345"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1artq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":66,"style":"ITALIC"},{"length":20,"offset":117,"style":"ITALIC"},{"length":20,"offset":170,"style":"ITALIC"},{"length":43,"offset":192,"style":"ITALIC"}],"text":"const str = \" Hello, World! \";\n\nconsole.log(str.trim()); // \"Hello, World!\"\nconsole.log(str.trimStart()); // \"Hello, World! \"\nconsole.log(str.trimEnd()); // \" Hello, World!\"\n\n// Частый кейс - очистка ввода пользователя\nconst userInput = \" admin \";\nconst cleanInput = userInput.trim();","type":"unstyled","key":"1cp8j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.5 Замена","type":"header-three","key":"59pdm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"annrl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":45,"offset":63,"style":"ITALIC"},{"length":43,"offset":155,"style":"ITALIC"},{"length":47,"offset":200,"style":"ITALIC"},{"length":35,"offset":297,"style":"ITALIC"},{"length":53,"offset":334,"style":"ITALIC"}],"text":"const str = \"JavaScript is awesome. JavaScript is powerful.\";\n\n// replace - заменяет только первое вхождение\nconsole.log(str.replace(\"JavaScript\", \"JS\"));\n// \"JS is awesome. JavaScript is powerful.\"\n\n// replaceAll - заменяет все вхождения (ES2021)\nconsole.log(str.replaceAll(\"JavaScript\", \"JS\"));\n// \"JS is awesome. JS is powerful.\"\n\n// Замена с регулярным выражением (глобальный флаг g)\nconsole.log(str.replace(/JavaScript/g, \"JS\"));","type":"unstyled","key":"fj2f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.6 Разделение и соединение","type":"header-three","key":"5svtd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fjcfv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":0,"style":"ITALIC"},{"length":32,"offset":114,"style":"ITALIC"},{"length":35,"offset":216,"style":"ITALIC"},{"length":23,"offset":253,"style":"ITALIC"},{"length":13,"offset":318,"style":"ITALIC"},{"length":25,"offset":333,"style":"ITALIC"},{"length":18,"offset":390,"style":"ITALIC"},{"length":25,"offset":410,"style":"ITALIC"},{"length":26,"offset":491,"style":"ITALIC"}],"text":"// split - строка → массив\nconst str = \"apple,banana,orange\";\nconst fruits = str.split(\",\");\nconsole.log(fruits); // [\"apple\", \"banana\", \"orange\"]\n\nconst words = \"Hello world from JS\".split(\" \");\nconsole.log(words); // [\"Hello\", \"world\", \"from\", \"JS\"]\n\n// split с ограничением\nconst limited = \"a,b,c,d\".split(\",\", 2); // [\"a\", \"b\"]\n\n// split по пустой строке\nconst chars = \"abc\".split(\"\"); // [\"a\", \"b\", \"c\"]\n\n// join - массив → строка\nconst joined = fruits.join(\"; \");\nconsole.log(joined); // \"apple; banana; orange\"","type":"unstyled","key":"72seh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.7 Повторение строки","type":"header-three","key":"5q0gl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9r5rl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":46,"style":"ITALIC"},{"length":25,"offset":87,"style":"ITALIC"}],"text":"const str = \"ha\";\nconsole.log(str.repeat(3)); // \"hahaha\"\nconsole.log(\"=\".repeat(20)); // \"====================\"","type":"unstyled","key":"4jv4v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. Сравнение строк","type":"header-two","key":"a9ivu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Строки сравниваются посимвольно на основе кодов Unicode.","type":"unstyled","key":"dakp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ca18k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":17,"offset":28,"style":"ITALIC"},{"length":19,"offset":74,"style":"ITALIC"},{"length":19,"offset":122,"style":"ITALIC"},{"length":39,"offset":143,"style":"ITALIC"},{"length":22,"offset":229,"style":"ITALIC"},{"length":4,"offset":298,"style":"ITALIC"},{"length":4,"offset":349,"style":"ITALIC"},{"length":29,"offset":355,"style":"ITALIC"},{"length":4,"offset":502,"style":"ITALIC"}],"text":"console.log(\"a\" < \"b\"); // true (97 < 98)\nconsole.log(\"ab\" < \"ac\"); // true ('b' < 'c')\nconsole.log(\"2\" > \"10\"); // true ('2' > '1')\n\n// Правильное сравнение с учётом локали\nconsole.log(\"apple\".localeCompare(\"banana\")); // -1 (apple < banana)\nconsole.log(\"banana\".localeCompare(\"apple\")); // 1\nconsole.log(\"apple\".localeCompare(\"apple\")); // 0\n\n// С учётом регистра и языков\nconst str1 = \"Straße\";\nconst str2 = \"STRASSE\";\nconsole.log(str1.localeCompare(str2, 'de', { sensitivity: 'base' })); // 0","type":"unstyled","key":"3f96t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Эмодзи и спецсимволы","type":"header-two","key":"86mn6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 Эмодзи в строках","type":"header-three","key":"3ff0f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"99dlc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":48,"style":"ITALIC"},{"length":47,"offset":78,"style":"ITALIC"},{"length":31,"offset":171,"style":"ITALIC"},{"length":27,"offset":204,"style":"ITALIC"},{"length":21,"offset":284,"style":"ITALIC"}],"text":"const smiley = \"\uD83D\uDE0A\";\nconsole.log(smiley.length); // 1 (в современных движках)\n\n// Некоторые эмодзи составные (например, флаги)\nconst flag = \"\uD83C\uDDFA\uD83C\uDDE6\";\nconsole.log(flag.length); // 2 (состоит из двух символов)\n\n// Семья (составной эмодзи)\nconst family = \"\uD83D\uDC68‍\uD83D\uDC69‍\uD83D\uDC67\";\nconsole.log(family.length); // 8 (много символов)","type":"unstyled","key":"1tj7f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 Экранирование","type":"header-three","key":"6rhqp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1mifc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":14,"offset":0,"style":"ITALIC"},{"length":9,"offset":127,"style":"ITALIC"},{"length":4,"offset":166,"style":"ITALIC"},{"length":10,"offset":200,"style":"ITALIC"},{"length":25,"offset":239,"style":"ITALIC"},{"length":4,"offset":295,"style":"ITALIC"},{"length":4,"offset":330,"style":"ITALIC"}],"text":"// Спецсимволы\nconst newline = \"Первая строка\\nВторая строка\";\nconst tab = \"Имя:\\tАнна\";\nconst backslash = \"C:\\\\Users\\\\Name\";\n\n// Юникод\nconst heart = \"\\u2764\"; // ❤\nconst smile = \"\\u{1F600}\"; // \uD83D\uDE00 (ES6)\nconsole.log(heart, smile);\n\n// Шестнадцатеричные коды\nconst copyright = \"\\xA9\"; // ©\nconst registered = \"\\xAE\"; // ®","type":"unstyled","key":"47hso"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Шаблонные строки - продвинутые техники","type":"header-two","key":"fdcp5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.1 Тегированные шаблоны","type":"header-three","key":"dot04"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3ok6s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":70,"offset":302,"style":"ITALIC"}],"text":"function highlight(strings, ...values) {\n return strings.reduce((result, str, i) => {\n return result + str + (values[i] ? `${values[i]}` : \"\");\n }, \"\");\n}\n\nconst name = \"Анна\";\nconst role = \"админ\";\nconst html = highlight`Пользователь ${name} с ролью ${role}`;\nconsole.log(html); // \"Пользователь Анна с ролью админ\"","type":"unstyled","key":"d8uc0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.2 Пользовательское экранирование","type":"header-three","key":"63l61"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3fupf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":65,"offset":508,"style":"ITALIC"}],"text":"function safe(strings, ...values) {\n const escape = (str) => {\n return str.replace(/[&<>]/g, (m) => {\n if (m === '&') return '&';\n if (m === '<') return '<';\n if (m === '>') return '>';\n return m;\n });\n };\n \n return strings.reduce((result, str, i) => {\n return result + str + (values[i] ? escape(String(values[i])) : \"\");\n }, \"\");\n}\n\nconst userInput = \"\";\nconst safeHtml = safe`Пользователь ввёл: ${userInput}`;\nconsole.log(safeHtml); // \"Пользователь ввёл: <script>alert('xss')</script>\"","type":"unstyled","key":"6lhlu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.3 Raw строки (без обработки escape-последовательностей)","type":"header-three","key":"8dtqp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ff78q"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":68,"style":"ITALIC"},{"length":53,"offset":190,"style":"ITALIC"}],"text":"const path = String.raw`C:\\Users\\Name\\file.txt`;\nconsole.log(path); // \"C:\\\\Users\\\\Name\\\\file.txt\"\n\nconst multilineRaw = String.raw`Первая строка\\nВторая строка`;\nconsole.log(multilineRaw); // \"Первая строка\\\\nВторая строка\" (\\n не обработано)","type":"unstyled","key":"9787n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Продвинутые методы (ES2020+)","type":"header-two","key":"673tk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.1 matchAll - все совпадения с группами","type":"header-three","key":"6ds4r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7ofek"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":14,"offset":158,"style":"ITALIC"},{"length":14,"offset":173,"style":"ITALIC"},{"length":13,"offset":188,"style":"ITALIC"}],"text":"const str = \"Цены: 100 руб, 250 руб, 30 руб\";\nconst regex = /(\\d+)\\s+руб/g;\n\nfor (const match of str.matchAll(regex)) {\n console.log(`Цена: ${match[1]}`);\n}\n// \"Цена: 100\"\n// \"Цена: 250\"\n// \"Цена: 30\"","type":"unstyled","key":"1m7u8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.2 replaceAll (уже упоминали)","type":"header-three","key":"67ljs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ajvo3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":24,"offset":66,"style":"ITALIC"}],"text":"const str = \"a+b+c+d\";\nconsole.log(str.replaceAll(\"+\", \" and \")); // \"a and b and c and d\"","type":"unstyled","key":"4jls7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.3 trimStart / trimEnd (ES2019)","type":"header-three","key":"929nq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6fj5j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":55,"style":"ITALIC"},{"length":12,"offset":98,"style":"ITALIC"}],"text":"const str = \" hello \";\nconsole.log(str.trimStart()); // \"hello \"\nconsole.log(str.trimEnd()); // \" hello\"","type":"unstyled","key":"en1nk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Преобразование в строку и из строки","type":"header-two","key":"peld"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.1 В строку","type":"header-three","key":"eof9s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1af7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":37,"offset":0,"style":"ITALIC"},{"length":8,"offset":57,"style":"ITALIC"},{"length":9,"offset":85,"style":"ITALIC"},{"length":9,"offset":114,"style":"ITALIC"},{"length":14,"offset":143,"style":"ITALIC"},{"length":43,"offset":159,"style":"ITALIC"},{"length":8,"offset":223,"style":"ITALIC"},{"length":9,"offset":252,"style":"ITALIC"},{"length":33,"offset":262,"style":"ITALIC"},{"length":52,"offset":297,"style":"ITALIC"},{"length":8,"offset":370,"style":"ITALIC"},{"length":9,"offset":399,"style":"ITALIC"}],"text":"// String() - предпочтительный способ\nString(123); // \"123\"\nString(true); // \"true\"\nString(null); // \"null\"\nString(undefined); // \"undefined\"\n\n// toString() - работает не со всеми типами\n(123).toString(); // \"123\"\ntrue.toString(); // \"true\"\n// null.toString(); // TypeError!\n\n// Конкатенация с пустой строкой (быстро, но неявно)\n123 + \"\"; // \"123\"\ntrue + \"\"; // \"true\"","type":"unstyled","key":"dash6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.2 Из строки","type":"header-three","key":"c8e1o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"260ho"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":0,"style":"ITALIC"},{"length":6,"offset":31,"style":"ITALIC"},{"length":6,"offset":58,"style":"ITALIC"},{"length":6,"offset":85,"style":"ITALIC"},{"length":7,"offset":114,"style":"ITALIC"},{"length":11,"offset":123,"style":"ITALIC"},{"length":24,"offset":156,"style":"ITALIC"},{"length":24,"offset":202,"style":"ITALIC"},{"length":11,"offset":228,"style":"ITALIC"},{"length":19,"offset":271,"style":"ITALIC"}],"text":"// В число\nNumber(\"123\"); // 123\n+\"123\"; // 123\nparseInt(\"123px\"); // 123\nparseFloat(\"3.14cm\"); // 3.14\n\n// В массив\nArray.from(\"hello\"); // [\"h\",\"e\",\"l\",\"l\",\"o\"]\n[...str]; // [\"h\",\"e\",\"l\",\"l\",\"o\"]\n\n// В объект\nJSON.parse('{\"name\":\"Анна\"}'); // { name: \"Анна\" }","type":"unstyled","key":"2jhvt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Производительность строк","type":"header-two","key":"d6n7r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.1 Конкатенация в циклах","type":"header-three","key":"ahi44"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"d48bb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":44,"offset":0,"style":"ITALIC"},{"length":25,"offset":116,"style":"ITALIC"}],"text":"// Плохо (создаёт много промежуточных строк)\nlet result = \"\";\nfor (let i = 0; i < 10000; i++) {\n result += \"a\";\n}\n\n// Хорошо (массив + join)\nconst parts = [];\nfor (let i = 0; i < 10000; i++) {\n parts.push(\"a\");\n}\nconst result = parts.join(\"\");","type":"unstyled","key":"4kq64"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"10.2 Шаблонные строки vs конкатенация","type":"header-three","key":"6a045"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"a1m1r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":57,"offset":38,"style":"ITALIC"},{"length":77,"offset":151,"style":"ITALIC"}],"text":"const name = \"Анна\";\nconst age = 25;\n\n// Шаблонные строки (читаемо, производительность хорошая)\nconst message1 = `Привет, ${name}! Тебе ${age} лет.`;\n\n// Конкатенация (было быстрее в старых движках, сейчас разница незначительна)\nconst message2 = \"Привет, \" + name + \"! Тебе \" + age + \" лет.\";","type":"unstyled","key":"bkfuo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Реальные кейсы","type":"header-two","key":"8lg6j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.1 Валидация email","type":"header-three","key":"3aqeg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9ta34"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":457,"style":"ITALIC"},{"length":8,"offset":512,"style":"ITALIC"}],"text":"function isValidEmail(email) {\n const trimmed = email.trim();\n if (!trimmed) return false;\n \n const atIndex = trimmed.indexOf('@');\n if (atIndex === -1 || atIndex === 0 || atIndex === trimmed.length - 1) {\n return false;\n }\n \n const dotIndex = trimmed.lastIndexOf('.');\n if (dotIndex === -1 || dotIndex < atIndex + 2 || dotIndex === trimmed.length - 1) {\n return false;\n }\n \n return true;\n}\n\nconsole.log(isValidEmail(\"user@example.com\")); // true\nconsole.log(isValidEmail(\"user@example\")); // false","type":"unstyled","key":"7lvll"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.2 Сокращение длинного текста","type":"header-three","key":"ah97c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"21jbp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":236,"style":"ITALIC"}],"text":"function truncate(text, maxLength, suffix = \"...\") {\n if (text.length <= maxLength) return text;\n return text.slice(0, maxLength - suffix.length) + suffix;\n}\n\nconsole.log(truncate(\"Очень длинный текст, который нужно сократить\", 20));\n// \"Очень длинный текст...\"","type":"unstyled","key":"ftt38"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.3 Капитализация первой буквы","type":"header-three","key":"471vp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"65q8b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":15,"offset":153,"style":"ITALIC"},{"length":9,"offset":208,"style":"ITALIC"}],"text":"function capitalize(str) {\n if (!str) return str;\n return str[0].toUpperCase() + str.slice(1).toLowerCase();\n}\n\nconsole.log(capitalize(\"javaSCRIPT\")); // \"Javascript\"\nconsole.log(capitalize(\"анна\")); // \"Анна\"","type":"unstyled","key":"fbsd5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.4 Склонение слов","type":"header-three","key":"3qh5h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"15iav"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":409,"style":"ITALIC"},{"length":10,"offset":464,"style":"ITALIC"},{"length":11,"offset":518,"style":"ITALIC"}],"text":"function pluralize(count, forms) {\n const remainder10 = count % 10;\n const remainder100 = count % 100;\n \n if (remainder100 >= 11 && remainder100 <= 19) {\n return forms[2];\n }\n if (remainder10 === 1) {\n return forms[0];\n }\n if (remainder10 >= 2 && remainder10 <= 4) {\n return forms[1];\n }\n return forms[2];\n}\n\nconst days = [\"день\", \"дня\", \"дней\"];\nconsole.log(`${1} ${pluralize(1, days)}`); // \"1 день\"\nconsole.log(`${3} ${pluralize(3, days)}`); // \"3 дня\"\nconsole.log(`${5} ${pluralize(5, days)}`); // \"5 дней\"","type":"unstyled","key":"aq1b1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.5 Генерация случайной строки","type":"header-three","key":"1u115"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"36dkl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":279,"style":"ITALIC"},{"length":15,"offset":338,"style":"ITALIC"}],"text":"function randomString(length, chars = \"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\") {\n let result = \"\";\n for (let i = 0; i < length; i++) {\n result += chars[Math.floor(Math.random() * chars.length)];\n }\n return result;\n}\n\nconsole.log(randomString(8)); // \"aB3xY7kL\"\nconsole.log(randomString(10, \"0123456789\")); // только цифры","type":"unstyled","key":"aakld"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"11.6 Подсчёт слов","type":"header-three","key":"3gr37"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fvat0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":4,"offset":174,"style":"ITALIC"},{"length":4,"offset":208,"style":"ITALIC"}],"text":"function countWords(text) {\n const words = text.trim().split(/\\s+/);\n return words[0] === \"\" ? 0 : words.length;\n}\n\nconsole.log(countWords(\"Hello world from JavaScript\")); // 4\nconsole.log(countWords(\"\")); // 0","type":"unstyled","key":"6vudh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Подводные камни","type":"header-two","key":"23oln"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #1: Сравнение строк с разными регистрами","type":"header-three","key":"9a8g1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"c0ak6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":34,"style":"ITALIC"},{"length":10,"offset":44,"style":"ITALIC"},{"length":7,"offset":117,"style":"ITALIC"}],"text":"console.log(\"Hello\" === \"hello\"); // false\n\n// Решение\nconsole.log(\"Hello\".toLowerCase() === \"hello\".toLowerCase()); // true","type":"unstyled","key":"cr3sd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #2: Пустая строка и пробелы","type":"header-three","key":"38kfo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7gqmb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":27,"style":"ITALIC"},{"length":37,"offset":81,"style":"ITALIC"},{"length":28,"offset":120,"style":"ITALIC"},{"length":19,"offset":175,"style":"ITALIC"}],"text":"console.log(\"\" == false); // true (приведение типов)\nconsole.log(\" \" == false); // true (строка с пробелом → число 0)\n\n// Всегда проверяйте .trim()\nif (userInput.trim()) {\n // не пустая строка\n}","type":"unstyled","key":"d6bb7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #3: Строковые индексы только для чтения","type":"header-three","key":"3946f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dgu7i"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":51,"style":"ITALIC"}],"text":"let str = \"hello\";\nstr[0] = \"H\";\nconsole.log(str); // \"hello\" (не изменилось!)","type":"unstyled","key":"9boca"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #4: substring и отрицательные индексы","type":"header-three","key":"7facu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dv7fo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":53,"style":"ITALIC"},{"length":36,"offset":116,"style":"ITALIC"}],"text":"const str = \"hello\";\nconsole.log(str.substring(-3)); // \"hello\" (отрицательное → 0)\nconsole.log(str.slice(-3)); // \"llo\" (работает с отрицательными)","type":"unstyled","key":"9468o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 13. Полезные трюки","type":"header-two","key":"5btr8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.1 Обратный порядок символов","type":"header-three","key":"iqgj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cefi1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":88,"style":"ITALIC"},{"length":24,"offset":100,"style":"ITALIC"},{"length":11,"offset":223,"style":"ITALIC"}],"text":"const reverse = str => str.split(\"\").reverse().join(\"\");\nconsole.log(reverse(\"hello\")); // \"olleh\"\n\n// С эмодзи (осторожно!)\nconst reverseUnicode = str => [...str].reverse().join(\"\");\nconsole.log(reverseUnicode(\"hello\uD83D\uDE0A\")); // \"\uD83D\uDE0Aolleh\"","type":"unstyled","key":"40je5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.2 Удаление всех пробелов","type":"header-three","key":"7l9dr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8ipvr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":64,"style":"ITALIC"}],"text":"const str = \" a b c \";\nconsole.log(str.replace(/\\s/g, \"\")); // \"abc\"","type":"unstyled","key":"5q0pl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.3 Проверка на палиндром","type":"header-three","key":"nc0h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6hlcq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":240,"style":"ITALIC"},{"length":8,"offset":284,"style":"ITALIC"}],"text":"function isPalindrome(str) {\n const cleaned = str.toLowerCase().replace(/[^а-яa-z]/g, \"\");\n const reversed = cleaned.split(\"\").reverse().join(\"\");\n return cleaned === reversed;\n}\n\nconsole.log(isPalindrome(\"А роза упала на лапу Азора\")); // true\nconsole.log(isPalindrome(\"hello\")); // false","type":"unstyled","key":"b4e5j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Манифест строк","type":"header-two","key":"2vn3f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":0,"style":"BOLD"}],"text":"Строки неизменяемы - любая операция создаёт новую строку.","type":"ordered-list-item","key":"49dmh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":0,"style":"BOLD"}],"text":"Три типа кавычек - одинарные, двойные, обратные (шаблонные).","type":"ordered-list-item","key":"2qe86"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":0,"style":"BOLD"}],"text":"Шаблонные строки - интерполяция, многострочность, тегирование.","type":"ordered-list-item","key":"9culh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":0,"style":"BOLD"}],"text":"Методы не меняют оригинал - всегда возвращают новую строку.","type":"ordered-list-item","key":"8aj6u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"length - количество символов (осторожно с эмодзи).","type":"ordered-list-item","key":"9j5il"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"slice - самый гибкий способ извлечения (поддерживает отрицательные индексы).","type":"ordered-list-item","key":"40p80"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"trim - всегда чистите пользовательский ввод.","type":"ordered-list-item","key":"9o09u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":3,"offset":8,"style":"BOLD"},{"length":3,"offset":21,"style":"BOLD"}],"text":"includes / startsWith / endsWith - современные методы поиска.","type":"ordered-list-item","key":"fnh7s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":20,"offset":0,"style":"BOLD"}],"text":"Регулярные выражения - мощь для сложного поиска и замены.","type":"ordered-list-item","key":"ejba3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":0,"style":"BOLD"}],"text":"Финальный тест (проверьте себя):","type":"unstyled","key":"9uuon"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"40rgc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"console.log(\"hello\"[0]);\nconsole.log(\"hello\".charAt(10));\nconsole.log(\"JavaScript\".slice(-4));\nconsole.log(\" test \".trim());\nconsole.log(\"a,b,c\".split(\",\").join(\"-\"));\nconsole.log(\"Hello\" + \" \" + \"World\");\nconsole.log(`2 + 2 = ${2 + 2}`);\nconsole.log(\"JavaScript\".replace(\"a\", \"o\"));\nconsole.log(\"JavaScript\".replaceAll(\"a\", \"o\"));\nconsole.log(\"\uD83E\uDD14\".length);","type":"unstyled","key":"e30gc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":0,"style":"BOLD"}],"text":"Ответы: \"h\", \"\" (пустая строка), \"ript\", \"test\", \"a-b-c\", \"Hello World\", \"2 + 2 = 4\", \"JovoScript\" (заменило только первое a), \"JovoScript\" (заменило все a), 1 (или 2 в старых движках).","type":"unstyled","key":"10d9t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Строки - это фундамент общения программы с миром. Они хранят имена, сообщения, данные. Умение работать со строками - это умение писать понятный, надёжный и безопасный код. Освойте их методы, и ваш код станет чище, а вы - увереннее. И пусть ваши строки всегда будут правильной длины!","type":"unstyled","key":"7e6ab"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"ft76q"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------------------","type":"unstyled","key":"6j9lj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"---------------------------------------------------------------------------------------------","type":"unstyled","key":"ajq3u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Укрощение стихии: Полное руководство по массивам в JavaScript","type":"header-two","key":"dvgtc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Массивы в JavaScript - это как швейцарский нож программиста. Они могут быть списком покупок, очередью задач, стеком вызовов, матрицей координат и даже деревом категорий. Они гибкие, динамические и полны сюрпризов.","type":"unstyled","key":"dis24"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Но с большой гибкостью приходит большая ответственность. Массивы в JS - это не просто \"списки элементов\". Это объекты с числовыми ключами, специальным свойством length и целой армией методов, которые могут менять, фильтровать, преобразовывать и агрегировать данные.","type":"unstyled","key":"334df"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Сегодня мы разберём массивы от А до Я: от создания до продвинутых техник работы.","type":"unstyled","key":"egkjq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Что такое массив?","type":"header-two","key":"7oatt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Массив - это упорядоченная коллекция элементов. В JavaScript массивы — это особый тип объектов с числовыми ключами (индексами) и специальным свойством length.","type":"unstyled","key":"5moo1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4mcmu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":76,"style":"ITALIC"},{"length":10,"offset":116,"style":"ITALIC"},{"length":4,"offset":155,"style":"ITALIC"}],"text":"const fruits = [\"яблоко\", \"банан\", \"апельсин\"];\nconsole.log(fruits[0]); // \"яблоко\"\nconsole.log(fruits[1]); // \"банан\"\nconsole.log(fruits.length); // 3","type":"unstyled","key":"7m6te"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":0,"style":"BOLD"}],"text":"Важное отличие от других языков: в JavaScript массивы могут содержать элементы разных типов.","type":"unstyled","key":"5fo0k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cqqbn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":5,"offset":94,"style":"ITALIC"},{"length":19,"offset":123,"style":"ITALIC"},{"length":12,"offset":166,"style":"ITALIC"}],"text":"const mixed = [42, \"строка\", true, null, { name: \"Анна\" }, [1, 2, 3]];\nconsole.log(mixed[0]); // 42\nconsole.log(mixed[4]); // { name: \"Анна\" }\nconsole.log(mixed[5]); // [1, 2, 3]","type":"unstyled","key":"h1bp"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. Создание массивов","type":"header-two","key":"4rhkb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.1 Литерал массива [] - самый простой и быстрый","type":"header-three","key":"47cig"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3f77s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":37,"style":"ITALIC"},{"length":12,"offset":90,"style":"ITALIC"},{"length":12,"offset":139,"style":"ITALIC"},{"length":12,"offset":188,"style":"ITALIC"}],"text":"const empty = []; // пустой массив\nconst numbers = [1, 2, 3]; // с числами\nconst mixed = [1, \"two\", true]; // смешанный\nconst nested = [[1, 2], [3, 4]]; // вложенный","type":"unstyled","key":"7an3g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.2 Конструктор Array()","type":"header-three","key":"56eb6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8gue5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":0,"style":"ITALIC"},{"length":52,"offset":44,"style":"ITALIC"},{"length":4,"offset":150,"style":"ITALIC"},{"length":56,"offset":181,"style":"ITALIC"},{"length":22,"offset":239,"style":"ITALIC"},{"length":12,"offset":314,"style":"ITALIC"},{"length":59,"offset":328,"style":"ITALIC"},{"length":17,"offset":417,"style":"ITALIC"},{"length":31,"offset":464,"style":"ITALIC"}],"text":"// Пустой массив\nconst arr1 = new Array();\n\n// Массив с заданной длиной (создаёт пустые \"дырки\")\nconst arr2 = new Array(5);\nconsole.log(arr2.length); // 5\nconsole.log(arr2[0]); // undefined (но это не то же самое, что пустой элемент)\n\n// Массив с элементами\nconst arr3 = new Array(1, 2, 3);\nconsole.log(arr3); // [1, 2, 3]\n\n// Осторожно: один числовой аргумент → длина, а не элемент!\nconst arr4 = new Array(5); // массив длины 5\nconst arr5 = new Array(\"5\"); // массив с одним элементом \"5\"","type":"unstyled","key":"foqs2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.3 Array.of() - решение проблемы конструктора","type":"header-three","key":"3vv48"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fo204"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":29,"style":"ITALIC"},{"length":12,"offset":89,"style":"ITALIC"}],"text":"console.log(Array.of(5)); // [5] (не массив длины 5!)\nconsole.log(Array.of(1, 2, 3)); // [1, 2, 3]","type":"unstyled","key":"ch33s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.4 Array.from() - из итерируемых объектов","type":"header-three","key":"est4l"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dko5n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":0,"style":"ITALIC"},{"length":28,"offset":47,"style":"ITALIC"},{"length":9,"offset":77,"style":"ITALIC"},{"length":12,"offset":149,"style":"ITALIC"},{"length":9,"offset":163,"style":"ITALIC"},{"length":23,"offset":246,"style":"ITALIC"},{"length":28,"offset":271,"style":"ITALIC"},{"length":12,"offset":348,"style":"ITALIC"},{"length":30,"offset":362,"style":"ITALIC"},{"length":18,"offset":446,"style":"ITALIC"}],"text":"// Из строки\nconsole.log(Array.from(\"hello\")); // [\"h\", \"e\", \"l\", \"l\", \"o\"]\n\n// Из Set\nconst set = new Set([1, 2, 3]);\nconsole.log(Array.from(set)); // [1, 2, 3]\n\n// Из Map\nconst map = new Map([[\"a\", 1], [\"b\", 2]]);\nconsole.log(Array.from(map)); // [[\"a\", 1], [\"b\", 2]]\n\n// С функцией преобразования\nconsole.log(Array.from([1, 2, 3], x => x * 2)); // [2, 4, 6]\n\n// Создание последовательности\nconsole.log(Array.from({ length: 5 }, (_, i) => i)); // [0, 1, 2, 3, 4]","type":"unstyled","key":"23vs8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Свойство length - друг или враг?","type":"header-two","key":"7ffeb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"length - это не просто количество элементов. Его можно изменять.","type":"unstyled","key":"a4fbb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1gqjb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":4,"offset":54,"style":"ITALIC"},{"length":37,"offset":60,"style":"ITALIC"},{"length":12,"offset":132,"style":"ITALIC"},{"length":46,"offset":146,"style":"ITALIC"},{"length":23,"offset":227,"style":"ITALIC"},{"length":29,"offset":272,"style":"ITALIC"},{"length":18,"offset":303,"style":"ITALIC"},{"length":5,"offset":356,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\nconsole.log(arr.length); // 5\n\n// Уменьшение длины - обрезает массив\narr.length = 3;\nconsole.log(arr); // [1, 2, 3]\n\n// Увеличение длины - добавляет пустые \"дырки\"\narr.length = 5;\nconsole.log(arr); // [1, 2, 3, empty × 2]\nconsole.log(arr[3]); // undefined (но ключа 3 нет)\n\n// Очистка массива\narr.length = 0;\nconsole.log(arr); // []","type":"unstyled","key":"4qkh5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Важно: length - это наибольший целочисленный индекс + 1.","type":"unstyled","key":"bg927"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3den3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":61,"style":"ITALIC"},{"length":25,"offset":93,"style":"ITALIC"}],"text":"const arr = [];\narr[10] = \"десять\";\nconsole.log(arr.length); // 11 (не 1!)\nconsole.log(arr); // [empty × 10, \"десять\"]","type":"unstyled","key":"db7r0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Основные операции с массивами","type":"header-two","key":"288i3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.1 Добавление и удаление элементов","type":"header-three","key":"964gq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8mkgc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":24,"style":"ITALIC"},{"length":40,"offset":55,"style":"ITALIC"},{"length":21,"offset":116,"style":"ITALIC"},{"length":11,"offset":139,"style":"ITALIC"},{"length":27,"offset":175,"style":"ITALIC"},{"length":11,"offset":204,"style":"ITALIC"},{"length":46,"offset":236,"style":"ITALIC"},{"length":12,"offset":284,"style":"ITALIC"},{"length":27,"offset":324,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\n\n// В конец\narr.push(4); // [1, 2, 3, 4] (возвращает новую длину)\narr.push(5, 6); // [1, 2, 3, 4, 5, 6]\n\n// Из конца\nconst last = arr.pop(); // 6, arr = [1, 2, 3, 4, 5]\n\n// В начало\narr.unshift(0); // [0, 1, 2, 3, 4, 5] (возвращает новую длину)\n\n// Из начала\nconst first = arr.shift(); // 0, arr = [1, 2, 3, 4, 5]","type":"unstyled","key":"blljr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.2 Удаление и вставка в середине (splice)","type":"header-three","key":"fla9r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"splice(start, deleteCount, ...items) - самый мощный метод.","type":"unstyled","key":"62k6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4lesj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":30,"style":"ITALIC"},{"length":33,"offset":76,"style":"ITALIC"},{"length":9,"offset":132,"style":"ITALIC"},{"length":12,"offset":164,"style":"ITALIC"},{"length":10,"offset":178,"style":"ITALIC"},{"length":40,"offset":213,"style":"ITALIC"},{"length":18,"offset":272,"style":"ITALIC"},{"length":9,"offset":292,"style":"ITALIC"},{"length":34,"offset":328,"style":"ITALIC"},{"length":20,"offset":381,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\n\n// Удаление\nconst deleted = arr.splice(2, 2); // удаляет 2 элемента с индекса 2\nconsole.log(deleted); // [3, 4]\nconsole.log(arr); // [1, 2, 5]\n\n// Вставка\narr.splice(2, 0, 3, 4); // на место 2, удалить 0, вставить 3 и 4\nconsole.log(arr); // [1, 2, 3, 4, 5]\n\n// Замена\narr.splice(1, 2, 20, 30); // заменить 2 элемента с индекса 1\nconsole.log(arr); // [1, 20, 30, 4, 5]","type":"unstyled","key":"ct5dt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.3 Извлечение части (slice)","type":"header-three","key":"asomm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"c9hgf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":35,"offset":61,"style":"ITALIC"},{"length":37,"offset":128,"style":"ITALIC"},{"length":33,"offset":197,"style":"ITALIC"},{"length":34,"offset":262,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\n\nconsole.log(arr.slice(2)); // [3, 4, 5] (с индекса 2 до конца)\nconsole.log(arr.slice(1, 4)); // [2, 3, 4] (с 1 до 4, не включая 4)\nconsole.log(arr.slice(-2)); // [4, 5] (отрицательные индексы)\nconsole.log(arr.slice()); // [1, 2, 3, 4, 5] (копия массива)","type":"unstyled","key":"9ljtq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. Итерация по массиву","type":"header-two","key":"c3im1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.1 Классический for","type":"header-three","key":"etrih"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"64nde"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"const arr = [\"a\", \"b\", \"c\"];\n\nfor (let i = 0; i < arr.length; i++) {\n console.log(arr[i]);\n}","type":"unstyled","key":"a0lge"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.2 for...of (для значений, не индексов)","type":"header-three","key":"4s1r5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"5dfnt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"for (const value of arr) {\n console.log(value);\n}","type":"unstyled","key":"3aum6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.3 forEach - функциональный подход","type":"header-three","key":"7pe2g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2drqm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"arr.forEach((value, index, array) => {\n console.log(`${index}: ${value}`);\n});","type":"unstyled","key":"dg2af"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.4 Сравнение методов итерации","type":"header-three","key":"fkd58"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"33n02"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":30,"style":"ITALIC"},{"length":29,"offset":94,"style":"ITALIC"},{"length":18,"offset":169,"style":"ITALIC"},{"length":22,"offset":189,"style":"ITALIC"},{"length":21,"offset":257,"style":"ITALIC"},{"length":4,"offset":333,"style":"ITALIC"},{"length":26,"offset":339,"style":"ITALIC"},{"length":7,"offset":409,"style":"ITALIC"},{"length":8,"offset":460,"style":"ITALIC"},{"length":27,"offset":470,"style":"ITALIC"},{"length":6,"offset":541,"style":"ITALIC"},{"length":4,"offset":593,"style":"ITALIC"}],"text":"const arr = [\"a\", \"b\", \"c\"];\n\n// forEach - просто итерация\narr.forEach(v => console.log(v));\n\n// map - создаёт новый массив\nconst upper = arr.map(v => v.toUpperCase()); // [\"A\", \"B\", \"C\"]\n\n// filter - фильтрация\nconst long = arr.filter(v => v.length > 1);\n\n// reduce - агрегация\nconst sum = [1, 2, 3].reduce((acc, v) => acc + v, 0); // 6\n\n// some / every - проверка\nconst hasA = arr.some(v => v === \"a\"); // true\nconst allA = arr.every(v => v === \"a\"); // false\n\n// find / findIndex - поиск\nconst found = arr.find(v => v === \"b\"); // \"b\"\nconst index = arr.findIndex(v => v === \"b\"); // 1","type":"unstyled","key":"844u0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Методы преобразования","type":"header-two","key":"cmjq4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 map - трансформация","type":"header-three","key":"d82d7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dlb6n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":96,"style":"ITALIC"},{"length":23,"offset":117,"style":"ITALIC"},{"length":43,"offset":194,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\nconst doubled = numbers.map(n => n * 2);\nconsole.log(doubled); // [2, 4, 6, 8, 10]\n\n// С доступом к индексу\nconst indexed = numbers.map((n, i) => `${i}: ${n}`);\n// [\"0: 1\", \"1: 2\", \"2: 3\", \"3: 4\", \"4: 5\"]","type":"unstyled","key":"3g4b4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 filter - отбор","type":"header-three","key":"6qpb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8tp29"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":102,"style":"ITALIC"},{"length":22,"offset":116,"style":"ITALIC"},{"length":57,"offset":319,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5, 6];\nconst even = numbers.filter(n => n % 2 === 0);\nconsole.log(even); // [2, 4, 6]\n\n// Фильтрация объектов\nconst users = [\n { name: \"Анна\", age: 25 },\n { name: \"Борис\", age: 17 },\n { name: \"Вика\", age: 30 }\n];\nconst adults = users.filter(user => user.age >= 18);\nconsole.log(adults); // [{ name: \"Анна\", age: 25 }, { name: \"Вика\", age: 30 }]","type":"unstyled","key":"aph6c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.3 reduce - свертка (самый мощный)","type":"header-three","key":"sqdq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"667a5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":34,"style":"ITALIC"},{"length":5,"offset":95,"style":"ITALIC"},{"length":15,"offset":102,"style":"ITALIC"},{"length":6,"offset":174,"style":"ITALIC"},{"length":11,"offset":182,"style":"ITALIC"},{"length":4,"offset":263,"style":"ITALIC"},{"length":14,"offset":269,"style":"ITALIC"},{"length":39,"offset":486,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Сумма\nconst sum = numbers.reduce((acc, n) => acc + n, 0); // 15\n\n// Произведение\nconst product = numbers.reduce((acc, n) => acc * n, 1); // 120\n\n// Максимум\nconst max = numbers.reduce((acc, n) => Math.max(acc, n), -Infinity); // 5\n\n// Группировка\nconst fruits = [\"яблоко\", \"банан\", \"яблоко\", \"апельсин\", \"банан\", \"банан\"];\nconst count = fruits.reduce((acc, fruit) => {\n acc[fruit] = (acc[fruit] || 0) + 1;\n return acc;\n}, {});\nconsole.log(count); // { яблоко: 2, банан: 3, апельсин: 1 }","type":"unstyled","key":"e1kvj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.4 flat и flatMap - работа с вложенностью","type":"header-three","key":"aljm0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6pqko"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":24,"offset":0,"style":"ITALIC"},{"length":23,"offset":99,"style":"ITALIC"},{"length":21,"offset":156,"style":"ITALIC"},{"length":23,"offset":214,"style":"ITALIC"},{"length":35,"offset":239,"style":"ITALIC"},{"length":52,"offset":407,"style":"ITALIC"}],"text":"// flat - разворачивание\nconst nested = [1, [2, 3], [4, [5, 6]]];\nconsole.log(nested.flat()); // [1, 2, 3, 4, [5, 6]]\nconsole.log(nested.flat(2)); // [1, 2, 3, 4, 5, 6]\nconsole.log(nested.flat(Infinity)); // полностью развернуть\n\n// flatMap - map + flat (глубина 1)\nconst sentences = [\"Hello world\", \"JavaScript is awesome\"];\nconst words = sentences.flatMap(s => s.split(\" \"));\nconsole.log(words); // [\"Hello\", \"world\", \"JavaScript\", \"is\", \"awesome\"]","type":"unstyled","key":"8kq8k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Поиск в массиве","type":"header-two","key":"62v2h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dd9tq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":37,"offset":33,"style":"ITALIC"},{"length":4,"offset":104,"style":"ITALIC"},{"length":24,"offset":142,"style":"ITALIC"},{"length":5,"offset":200,"style":"ITALIC"},{"length":44,"offset":207,"style":"ITALIC"},{"length":4,"offset":285,"style":"ITALIC"},{"length":30,"offset":291,"style":"ITALIC"},{"length":7,"offset":355,"style":"ITALIC"},{"length":8,"offset":396,"style":"ITALIC"},{"length":35,"offset":406,"style":"ITALIC"},{"length":4,"offset":498,"style":"ITALIC"},{"length":39,"offset":504,"style":"ITALIC"},{"length":4,"offset":601,"style":"ITALIC"},{"length":52,"offset":607,"style":"ITALIC"},{"length":4,"offset":728,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5, 2];\n\n// indexOf - индекс первого вхождения\nconsole.log(arr.indexOf(2)); // 1\nconsole.log(arr.indexOf(2, 2)); // 5 (поиск с индекса 2)\nconsole.log(arr.indexOf(10)); // -1\n\n// lastIndexOf - индекс последнего вхождения\nconsole.log(arr.lastIndexOf(2)); // 5\n\n// includes - проверка наличия\nconsole.log(arr.includes(3)); // true\nconsole.log(arr.includes(10)); // false\n\n// find - поиск элемента по условию\nconst found = arr.find(n => n > 3);\nconsole.log(found); // 4\n\n// findIndex - поиск индекса по условию\nconst idx = arr.findIndex(n => n > 3);\nconsole.log(idx); // 3\n\n// findLast / findLastIndex (ES2023) - поиск с конца\nconst lastFound = arr.findLast(n => n > 3);\nconsole.log(lastFound); // 5","type":"unstyled","key":"bhsi8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Сортировка и порядок","type":"header-two","key":"8ov6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.1 sort() - коварный метод","type":"header-three","key":"6ghpn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"5fopo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":48,"offset":41,"style":"ITALIC"},{"length":39,"offset":128,"style":"ITALIC"},{"length":23,"offset":169,"style":"ITALIC"},{"length":42,"offset":246,"style":"ITALIC"},{"length":14,"offset":290,"style":"ITALIC"},{"length":25,"offset":358,"style":"ITALIC"}],"text":"const numbers = [1, 30, 4, 21, 100000];\n\n// Без функции сравнения (сортирует как строки!)\nnumbers.sort();\nconsole.log(numbers); // [1, 100000, 21, 30, 4] (по строкам!)\n\n// С функцией сравнения\nnumbers.sort((a, b) => a - b);\nconsole.log(numbers); // [1, 4, 21, 30, 100000] (по возрастанию)\n\n// По убыванию\nnumbers.sort((a, b) => b - a);\nconsole.log(numbers); // [100000, 30, 21, 4, 1]","type":"unstyled","key":"9kh59"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Важно: sort() изменяет исходный массив.","type":"unstyled","key":"b25jm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9ss9h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":79,"style":"ITALIC"}],"text":"const arr = [3, 1, 2];\nconst sorted = arr.sort();\nconsole.log(arr === sorted); // true (один и тот же массив)","type":"unstyled","key":"et78d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.2 reverse() - обратный порядок","type":"header-three","key":"190ra"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"a5tek"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":38,"offset":62,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\narr.reverse();\nconsole.log(arr); // [5, 4, 3, 2, 1] (изменяет исходный)","type":"unstyled","key":"5tl55"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.3 toSorted() и toReversed() (ES2023) - без мутации","type":"header-three","key":"c6v2c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"41o7v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":54,"style":"ITALIC"},{"length":12,"offset":102,"style":"ITALIC"},{"length":27,"offset":133,"style":"ITALIC"}],"text":"const arr = [3, 1, 2];\nconst sorted = arr.toSorted(); // [1, 2, 3]\nconst reversed = arr.toReversed(); // [2, 1, 3]\nconsole.log(arr); // [3, 1, 2] (не изменился)","type":"unstyled","key":"co73g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Специальные методы","type":"header-two","key":"1asi7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.1 join() - склеивание в строку","type":"header-three","key":"8f2qo"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fu6g4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":83,"style":"ITALIC"},{"length":28,"offset":145,"style":"ITALIC"},{"length":30,"offset":209,"style":"ITALIC"},{"length":24,"offset":275,"style":"ITALIC"}],"text":"const fruits = [\"яблоко\", \"банан\", \"апельсин\"];\nconsole.log(fruits.join()); // \"яблоко,банан,апельсин\"\nconsole.log(fruits.join(\", \")); // \"яблоко, банан, апельсин\"\nconsole.log(fruits.join(\" и \")); // \"яблоко и банан и апельсин\"\nconsole.log(fruits.join(\"\")); // \"яблокобананапельсин\"","type":"unstyled","key":"ceanl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.2 concat() - объединение массивов","type":"header-three","key":"bnlan"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"dlhkj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":129,"style":"ITALIC"},{"length":30,"offset":152,"style":"ITALIC"}],"text":"const arr1 = [1, 2];\nconst arr2 = [3, 4];\nconst arr3 = [5, 6];\n\nconst combined = arr1.concat(arr2, arr3);\nconsole.log(combined); // [1, 2, 3, 4, 5, 6]\n\n// Современный способ (spread)\nconst combined2 = [...arr1, ...arr2, ...arr3];","type":"unstyled","key":"4cone"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.3 fill() - заполнение","type":"header-three","key":"1a5jb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bb5or"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":57,"style":"ITALIC"},{"length":32,"offset":96,"style":"ITALIC"},{"length":18,"offset":147,"style":"ITALIC"}],"text":"const arr = new Array(5);\narr.fill(0);\nconsole.log(arr); // [0, 0, 0, 0, 0]\n\narr.fill(1, 2, 4); // с индекса 2 до 4 (не включая)\nconsole.log(arr); // [0, 0, 1, 1, 0]","type":"unstyled","key":"93bc0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.4 copyWithin() - копирование внутри массива","type":"header-three","key":"c0meb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"r670"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":45,"offset":54,"style":"ITALIC"},{"length":18,"offset":118,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\narr.copyWithin(0, 3, 5); // скопировать элементы с 3 по 5 на позицию 0\nconsole.log(arr); // [4, 5, 3, 4, 5]","type":"unstyled","key":"behhk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Проверка на массив","type":"header-two","key":"caa5m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4ssd8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":65,"style":"ITALIC"},{"length":36,"offset":92,"style":"ITALIC"},{"length":7,"offset":162,"style":"ITALIC"},{"length":8,"offset":203,"style":"ITALIC"},{"length":59,"offset":213,"style":"ITALIC"},{"length":7,"offset":308,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\nconst obj = {};\n\nconsole.log(typeof arr); // \"object\" (не поможет!)\n\n// Array.isArray - правильный способ\nconsole.log(Array.isArray(arr)); // true\nconsole.log(Array.isArray(obj)); // false\n\n// instanceof (работает, но может ошибаться между фреймами)\nconsole.log(arr instanceof Array); // true","type":"unstyled","key":"ctr2c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Деструктуризация массивов","type":"header-two","key":"amfqa"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9a9p3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":34,"style":"ITALIC"},{"length":10,"offset":94,"style":"ITALIC"},{"length":20,"offset":106,"style":"ITALIC"},{"length":7,"offset":188,"style":"ITALIC"},{"length":29,"offset":197,"style":"ITALIC"},{"length":4,"offset":279,"style":"ITALIC"},{"length":15,"offset":303,"style":"ITALIC"},{"length":24,"offset":320,"style":"ITALIC"},{"length":7,"offset":391,"style":"ITALIC"},{"length":19,"offset":400,"style":"ITALIC"},{"length":7,"offset":474,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Базовая\nconst [a, b, c] = numbers;\nconsole.log(a, b, c); // 1, 2, 3\n\n// Пропуск элементов\nconst [first, , third] = numbers;\nconsole.log(first, third); // 1, 3\n\n// Остаточные элементы (rest)\nconst [head, ...tail] = numbers;\nconsole.log(head); // 1\nconsole.log(tail); // [2, 3, 4, 5]\n\n// Значения по умолчанию\nconst [x = 0, y = 0] = [];\nconsole.log(x, y); // 0, 0\n\n// Обмен переменных\nlet i = 1, j = 2;\n[i, j] = [j, i];\nconsole.log(i, j); // 2, 1","type":"unstyled","key":"2fskc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Массив как стек и очередь","type":"header-two","key":"aevf6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Стек (LIFO - последним пришёл, первым ушёл)","type":"header-three","key":"ad9qu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"evsip"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":39,"style":"ITALIC"},{"length":12,"offset":72,"style":"ITALIC"},{"length":12,"offset":110,"style":"ITALIC"},{"length":4,"offset":144,"style":"ITALIC"},{"length":9,"offset":170,"style":"ITALIC"}],"text":"const stack = [];\nstack.push(1, 2, 3); // добавляем\nconsole.log(stack); // [1, 2, 3]\nconst top = stack.pop(); // извлекаем\nconsole.log(top); // 3\nconsole.log(stack); // [1, 2]","type":"unstyled","key":"enghh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Очередь (FIFO - первым пришёл, первым ушёл)","type":"header-three","key":"9cm3h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"diuer"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":20,"offset":40,"style":"ITALIC"},{"length":12,"offset":83,"style":"ITALIC"},{"length":22,"offset":125,"style":"ITALIC"},{"length":4,"offset":170,"style":"ITALIC"},{"length":9,"offset":197,"style":"ITALIC"}],"text":"const queue = [];\nqueue.push(1, 2, 3); // добавляем в конец\nconsole.log(queue); // [1, 2, 3]\nconst front = queue.shift(); // извлекаем из начала\nconsole.log(front); // 1\nconsole.log(queue); // [2, 3]","type":"unstyled","key":"7s3nq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 13. Реальные паттерны","type":"header-two","key":"8ci0s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.1 Уникальные значения","type":"header-three","key":"c1v08"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"ftes"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":101,"style":"ITALIC"}],"text":"const numbers = [1, 2, 2, 3, 3, 4, 5, 5];\nconst unique = [...new Set(numbers)];\nconsole.log(unique); // [1, 2, 3, 4, 5]","type":"unstyled","key":"akn98"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.2 Пересечение массивов","type":"header-three","key":"9a04q"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bgokh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":9,"offset":138,"style":"ITALIC"}],"text":"const arr1 = [1, 2, 3, 4];\nconst arr2 = [3, 4, 5, 6];\nconst intersection = arr1.filter(x => arr2.includes(x));\nconsole.log(intersection); // [3, 4]","type":"unstyled","key":"bch7j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.3 Разность массивов","type":"header-three","key":"10ev8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"f1e8q"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":9,"offset":135,"style":"ITALIC"}],"text":"const arr1 = [1, 2, 3, 4];\nconst arr2 = [3, 4, 5, 6];\nconst difference = arr1.filter(x => !arr2.includes(x));\nconsole.log(difference); // [1, 2]","type":"unstyled","key":"78mg5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.4 Группировка по свойству","type":"header-three","key":"9s7fi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cgkei"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":4,"offset":320,"style":"ITALIC"},{"length":82,"offset":325,"style":"ITALIC"},{"length":73,"offset":408,"style":"ITALIC"},{"length":4,"offset":482,"style":"ITALIC"}],"text":"const users = [\n { name: \"Анна\", city: \"Москва\" },\n { name: \"Борис\", city: \"СПб\" },\n { name: \"Вика\", city: \"Москва\" },\n { name: \"Глеб\", city: \"СПб\" }\n];\n\nconst byCity = users.reduce((acc, user) => {\n if (!acc[user.city]) acc[user.city] = [];\n acc[user.city].push(user);\n return acc;\n}, {});\n\nconsole.log(byCity);\n// {\n// Москва: [{ name: \"Анна\", city: \"Москва\" }, { name: \"Вика\", city: \"Москва\" }],\n// СПб: [{ name: \"Борис\", city: \"СПб\" }, { name: \"Глеб\", city: \"СПб\" }]\n// }","type":"unstyled","key":"bghmn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.5 Плоский массив (любой глубины)","type":"header-three","key":"1eek4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"640or"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":217,"style":"ITALIC"}],"text":"function flattenDeep(arr) {\n return arr.reduce((acc, val) => {\n return acc.concat(Array.isArray(val) ? flattenDeep(val) : val);\n }, []);\n}\n\nconst nested = [1, [2, [3, [4, 5]]]];\nconsole.log(flattenDeep(nested)); // [1, 2, 3, 4, 5]","type":"unstyled","key":"1ki8k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.6 Разбивка на чанки","type":"header-three","key":"6kjh6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3l2oi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":232,"style":"ITALIC"}],"text":"function chunk(array, size) {\n return array.reduce((acc, _, i) => {\n if (i % size === 0) acc.push(array.slice(i, i + size));\n return acc;\n }, []);\n}\n\nconst numbers = [1, 2, 3, 4, 5, 6, 7, 8];\nconsole.log(chunk(numbers, 3)); // [[1,2,3], [4,5,6], [7,8]]","type":"unstyled","key":"2k8a4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"13.7 Очередь с ограничением (LRU Cache)","type":"header-three","key":"83f9p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8o0ru"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":114,"style":"ITALIC"},{"length":20,"offset":244,"style":"ITALIC"},{"length":32,"offset":301,"style":"ITALIC"},{"length":12,"offset":573,"style":"ITALIC"},{"length":12,"offset":626,"style":"ITALIC"}],"text":"class LRUCache {\n constructor(limit = 5) {\n this.limit = limit;\n this.cache = [];\n }\n \n add(item) {\n // Удаляем, если уже есть\n const index = this.cache.indexOf(item);\n if (index !== -1) this.cache.splice(index, 1);\n \n // Добавляем в конец\n this.cache.push(item);\n \n // Обрезаем, если превышен лимит\n if (this.cache.length > this.limit) {\n this.cache.shift();\n }\n }\n \n get() {\n return [...this.cache];\n }\n}\n\nconst cache = new LRUCache(3);\ncache.add(1); cache.add(2); cache.add(3); cache.add(4);\nconsole.log(cache.get()); // [2, 3, 4]\ncache.add(2);\nconsole.log(cache.get()); // [3, 4, 2]","type":"unstyled","key":"b49jr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 14. Подводные камни","type":"header-two","key":"7inq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #1: delete не удаляет элемент правильно","type":"header-three","key":"epfb0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"es9c8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":61,"style":"ITALIC"},{"length":27,"offset":103,"style":"ITALIC"},{"length":20,"offset":132,"style":"ITALIC"},{"length":9,"offset":189,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\ndelete arr[1];\nconsole.log(arr); // [1, empty, 3]\nconsole.log(arr.length); // 3 (длина не изменилась!)\n\n// Правильно: splice\narr.splice(1, 1);\nconsole.log(arr); // [1, 3]","type":"unstyled","key":"9vodn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #2: Массивы - это объекты","type":"header-three","key":"941fl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"5j80s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":78,"style":"ITALIC"},{"length":20,"offset":118,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\narr.customProp = \"hello\";\nconsole.log(arr.customProp); // \"hello\"\nconsole.log(arr.length); // 3 (не изменилась)","type":"unstyled","key":"7pp8f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #3: for...in для массивов - плохо","type":"header-three","key":"bmgr5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6jfj9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":51,"offset":93,"style":"ITALIC"},{"length":28,"offset":195,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\narr.customProp = \"hello\";\n\nfor (let key in arr) {\n console.log(key); // \"0\", \"1\", \"2\", \"customProp\" (включает свойства!)\n}\n\nfor (let value of arr) {\n console.log(value); // 1, 2, 3 (только элементы)\n}","type":"unstyled","key":"61hd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #4: Сравнение массивов","type":"header-three","key":"2phlk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4tod4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":76,"style":"ITALIC"},{"length":24,"offset":103,"style":"ITALIC"},{"length":7,"offset":284,"style":"ITALIC"}],"text":"const arr1 = [1, 2, 3];\nconst arr2 = [1, 2, 3];\nconsole.log(arr1 === arr2); // false (разные объекты)\n\n// Сравнение содержимого\nfunction arraysEqual(a, b) {\n if (a.length !== b.length) return false;\n return a.every((val, i) => val === b[i]);\n}\nconsole.log(arraysEqual(arr1, arr2)); // true","type":"unstyled","key":"cul19"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Манифест массивов","type":"header-two","key":"9e2fm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":0,"style":"BOLD"}],"text":"Массивы - это объекты с числовыми ключами и свойством length.","type":"ordered-list-item","key":"b88r1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":15,"offset":6,"style":"BOLD"}],"text":"length можно изменять - обрезать и расширять массив.","type":"ordered-list-item","key":"5rj0g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":43,"offset":0,"style":"BOLD"}],"text":"Методы делятся на мутирующие и немутирующие:\nМутируют: push, pop, shift, unshift, splice, sort, reverse, fill, copyWithin\nНе мутируют: slice, concat, map, filter, reduce, forEach, find, includes","type":"ordered-list-item","key":"bdgri"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":6,"style":"BOLD"}],"text":"sort() без функции сравнения - сортирует как строки (коварно!).","type":"ordered-list-item","key":"e8bf2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Array.isArray() - единственный надёжный способ проверки.","type":"ordered-list-item","key":"mhvs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":0,"style":"BOLD"}],"text":"Деструктуризация - удобно для обмена переменных и извлечения элементов.","type":"ordered-list-item","key":"a47d0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"},{"length":1,"offset":11,"style":"BOLD"}],"text":"Spread (...) - современная альтернатива concat().","type":"ordered-list-item","key":"1vber"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":32,"offset":0,"style":"BOLD"}],"text":"Финальный тест (проверьте себя):","type":"unstyled","key":"a1jme"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"85s4o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"const arr = [1, 2, 3];\narr[10] = 10;\nconsole.log(arr.length);\n\nconst arr2 = [1, 2, 3];\nconst result = arr2.map(x => x * 2);\nconsole.log(arr2);\n\nconst arr3 = [1, 2, 3, 4, 5];\narr3.splice(2, 2);\nconsole.log(arr3);\n\nconst arr4 = [1, 2, 3];\nconst [a, , c] = arr4;\nconsole.log(a, c);","type":"unstyled","key":"3g1i"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":0,"style":"BOLD"}],"text":"Ответы: 11, [1, 2, 3] (map не изменяет оригинал), [1, 2, 5], 1, 3.","type":"unstyled","key":"2hvr3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Массивы - это рабочие лошадки JavaScript. Они везде: в обработке данных, в работе с DOM, в API, в состоянии приложений. Освойте их методы, и вы сможете выражать сложные операции в одной строке кода. Помните: хороший код - это не тот, который работает, а тот, который понятен. Используйте массивы с умом, и ваши коллеги скажут вам спасибо.","type":"unstyled","key":"886dl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"9ssrt"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"--------------------------------------------------------------------------------------","type":"unstyled","key":"8s346"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"--------------------------------------------------------------------------------------","type":"unstyled","key":"ftrsu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Армия методов: Как массивы JavaScript стали самыми мощными инструментами в истории языка","type":"header-two","key":"fdnt9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Массивы в JavaScript - это не просто \"списки элементов\". Это настоящий швейцарский арсенал. Если вы всё ещё используете for (let i = 0; i < arr.length; i++) для всего подряд - вы тратите свою жизнь впустую.","type":"unstyled","key":"3hd25"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":3,"offset":86,"style":"BOLD"},{"length":3,"offset":119,"style":"BOLD"}],"text":"Методы массивов - это декларативная революция. Вместо того чтобы объяснять компьютеру как итерировать, вы говорите ему что сделать. map для трансформации, filter для отбора, reduce для агрегации. Это не просто удобно - это меняет способ мышления о данных.","type":"unstyled","key":"5k7jf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Сегодня мы пройдём по всем методам массивов: от священной троицы (map/filter/reduce) до экзотических flatMap, with и группировки.","type":"unstyled","key":"142su"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Почему методы массивов лучше циклов?","type":"header-two","key":"2cdb2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7p8pi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":0,"style":"ITALIC"},{"length":28,"offset":160,"style":"ITALIC"}],"text":"// Старый мир (императивный)\nconst numbers = [1, 2, 3, 4, 5];\nconst doubled = [];\nfor (let i = 0; i < numbers.length; i++) {\n doubled.push(numbers[i] * 2);\n}\n\n// Новый мир (декларативный)\nconst doubled = numbers.map(n => n * 2);","type":"unstyled","key":"6irnu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"}],"text":"Разница:","type":"unstyled","key":"5lp2c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Короче - одна строка вместо пяти","type":"unordered-list-item","key":"d7h11"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"}],"text":"Читаемее - сразу понятно, что происходит","type":"unordered-list-item","key":"14euj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":0,"style":"BOLD"}],"text":"Без побочных эффектов - не мутирует исходный массив","type":"unordered-list-item","key":"5lbur"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":0,"style":"BOLD"}],"text":"Легче комбинировать - цепочки методов","type":"unordered-list-item","key":"am53j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. Священная троица: map, filter, reduce","type":"header-two","key":"4u669"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.1 map - трансформация каждого элемента","type":"header-three","key":"ahhrs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":12,"style":"BOLD"}],"text":"map создаёт новый массив, применяя функцию к каждому элементу.","type":"unstyled","key":"bgqcc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"56bl0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":34,"style":"ITALIC"},{"length":19,"offset":109,"style":"ITALIC"},{"length":21,"offset":130,"style":"ITALIC"},{"length":28,"offset":322,"style":"ITALIC"},{"length":23,"offset":352,"style":"ITALIC"},{"length":43,"offset":451,"style":"ITALIC"},{"length":33,"offset":496,"style":"ITALIC"},{"length":18,"offset":621,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Удвоение\nconst doubled = numbers.map(n => n * 2);\nconsole.log(doubled); // [2, 4, 6, 8, 10]\n\n// Извлечение свойств\nconst users = [\n { name: \"Анна\", age: 25 },\n { name: \"Борис\", age: 30 },\n { name: \"Вика\", age: 28 }\n];\nconst names = users.map(user => user.name);\nconsole.log(names); // [\"Анна\", \"Борис\", \"Вика\"]\n\n// С доступом к индексу\nconst indexed = numbers.map((n, i) => `${i}: ${n}`);\nconsole.log(indexed); // [\"0: 1\", \"1: 2\", \"2: 3\", \"3: 4\", \"4: 5\"]\n\n// С доступом к исходному массиву\nconst withPrev = numbers.map((n, i, arr) => n + (arr[i - 1] || 0));\nconsole.log(withPrev); // [1, 3, 5, 7, 9]","type":"unstyled","key":"ed8ls"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.2 filter - отбор элементов","type":"header-three","key":"8n8nk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":15,"style":"BOLD"}],"text":"filter создаёт новый массив с элементами, прошедшими проверку.","type":"unstyled","key":"2b9c6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"epjj6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":15,"offset":50,"style":"ITALIC"},{"length":19,"offset":134,"style":"ITALIC"},{"length":26,"offset":155,"style":"ITALIC"},{"length":15,"offset":311,"style":"ITALIC"},{"length":22,"offset":328,"style":"ITALIC"},{"length":30,"offset":425,"style":"ITALIC"},{"length":39,"offset":457,"style":"ITALIC"},{"length":18,"offset":650,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];\n\n// Чётные числа\nconst evens = numbers.filter(n => n % 2 === 0);\nconsole.log(evens); // [2, 4, 6, 8, 10]\n\n// Удаление null/undefined\nconst withNulls = [1, null, 2, undefined, 3, null, 4];\nconst clean = withNulls.filter(item => item != null);\nconsole.log(clean); // [1, 2, 3, 4]\n\n// Фильтрация объектов\nconst adults = users.filter(user => user.age >= 18);\nconsole.log(adults); // все пользователи (все >=18)\n\n// Уникальные значения (простой способ)\nconst duplicates = [1, 2, 2, 3, 3, 4, 5, 5];\nconst unique = duplicates.filter((value, index, arr) => arr.indexOf(value) === index);\nconsole.log(unique); // [1, 2, 3, 4, 5]","type":"unstyled","key":"3420l"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"2.3 reduce - агрегация всего и вся","type":"header-three","key":"17eqb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"reduce - самый мощный метод. Он свёртывает массив в одно значение.","type":"unstyled","key":"9mg2d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"aitri"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":34,"style":"ITALIC"},{"length":5,"offset":113,"style":"ITALIC"},{"length":15,"offset":120,"style":"ITALIC"},{"length":6,"offset":214,"style":"ITALIC"},{"length":11,"offset":222,"style":"ITALIC"},{"length":4,"offset":321,"style":"ITALIC"},{"length":17,"offset":327,"style":"ITALIC"},{"length":39,"offset":547,"style":"ITALIC"},{"length":26,"offset":588,"style":"ITALIC"},{"length":57,"offset":798,"style":"ITALIC"},{"length":31,"offset":857,"style":"ITALIC"},{"length":21,"offset":1012,"style":"ITALIC"},{"length":18,"offset":1035,"style":"ITALIC"},{"length":20,"offset":1250,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Сумма\nconst sum = numbers.reduce((acc, n) => acc + n, 0);\nconsole.log(sum); // 15\n\n// Произведение\nconst product = numbers.reduce((acc, n) => acc * n, 1);\nconsole.log(product); // 120\n\n// Максимум\nconst max = numbers.reduce((acc, n) => Math.max(acc, n), -Infinity);\nconsole.log(max); // 5\n\n// Объект-счётчик\nconst fruits = [\"яблоко\", \"банан\", \"яблоко\", \"апельсин\", \"банан\", \"банан\"];\nconst count = fruits.reduce((acc, fruit) => {\n acc[fruit] = (acc[fruit] || 0) + 1;\n return acc;\n}, {});\nconsole.log(count); // { яблоко: 2, банан: 3, апельсин: 1 }\n\n// Группировка по свойству\nconst grouped = users.reduce((acc, user) => {\n const firstLetter = user.name[0];\n if (!acc[firstLetter]) acc[firstLetter] = [];\n acc[firstLetter].push(user);\n return acc;\n}, {});\n// { А: [{ name: \"Анна\", age: 25 }], Б: [...], В: [...] }\n\n// Плоский массив из вложенного\nconst nested = [[1, 2], [3, 4], [5, 6]];\nconst flat = nested.reduce((acc, arr) => acc.concat(arr), []);\nconsole.log(flat); // [1, 2, 3, 4, 5, 6]\n\n// Цепочка функций\nconst pipe = (...fns) => x => fns.reduce((acc, fn) => fn(acc), x);\nconst double = x => x * 2;\nconst addOne = x => x + 1;\nconst square = x => x * x;\nconst result = pipe(double, addOne, square)(5); // ((5*2)+1)^2 = 121","type":"unstyled","key":"6kuhq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Методы поиска","type":"header-two","key":"t8op"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.1 find и findIndex - первый подходящий","type":"header-three","key":"e4pof"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bbjqs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":45,"offset":128,"style":"ITALIC"},{"length":26,"offset":248,"style":"ITALIC"},{"length":15,"offset":276,"style":"ITALIC"},{"length":4,"offset":373,"style":"ITALIC"},{"length":26,"offset":379,"style":"ITALIC"},{"length":12,"offset":480,"style":"ITALIC"},{"length":5,"offset":583,"style":"ITALIC"}],"text":"const users = [\n { id: 1, name: \"Анна\" },\n { id: 2, name: \"Борис\" },\n { id: 3, name: \"Вика\" },\n { id: 4, name: \"Анна\" }\n];\n\n// Найти первого пользователя с именем \"Анна\"\nconst anna = users.find(user => user.name === \"Анна\");\nconsole.log(anna); // { id: 1, name: \"Анна\" }\n\n// Найти индекс\nconst index = users.findIndex(user => user.name === \"Анна\");\nconsole.log(index); // 0\n\n// Когда ничего не найдено\nconst none = users.find(user => user.name === \"Глеб\");\nconsole.log(none); // undefined\n\nconst noneIndex = users.findIndex(user => user.name === \"Глеб\");\nconsole.log(noneIndex); // -1","type":"unstyled","key":"61bp0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.2 findLast и findLastIndex (ES2023) — с конца","type":"header-three","key":"4bgeb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fagvv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":48,"offset":128,"style":"ITALIC"},{"length":26,"offset":263,"style":"ITALIC"},{"length":4,"offset":384,"style":"ITALIC"}],"text":"const users = [\n { id: 1, name: \"Анна\" },\n { id: 2, name: \"Борис\" },\n { id: 3, name: \"Вика\" },\n { id: 4, name: \"Анна\" }\n];\n\n// Найти последнего пользователя с именем \"Анна\"\nconst lastAnna = users.findLast(user => user.name === \"Анна\");\nconsole.log(lastAnna); // { id: 4, name: \"Анна\" }\n\nconst lastIndex = users.findLastIndex(user => user.name === \"Анна\");\nconsole.log(lastIndex); // 3","type":"unstyled","key":"1brln"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.3 indexOf и lastIndexOf - для примитивов","type":"header-three","key":"1mpat"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9tcg7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":4,"offset":74,"style":"ITALIC"},{"length":24,"offset":116,"style":"ITALIC"},{"length":5,"offset":178,"style":"ITALIC"},{"length":4,"offset":222,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5, 2];\n\nconsole.log(numbers.indexOf(2)); // 1\nconsole.log(numbers.indexOf(2, 2)); // 5 (поиск с индекса 2)\nconsole.log(numbers.indexOf(10)); // -1\n\nconsole.log(numbers.lastIndexOf(2)); // 5","type":"unstyled","key":"4kcqh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.4 includes - проверка наличия","type":"header-three","key":"a76me"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bvtja"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":90,"style":"ITALIC"},{"length":8,"offset":139,"style":"ITALIC"},{"length":28,"offset":190,"style":"ITALIC"}],"text":"const fruits = [\"яблоко\", \"банан\", \"апельсин\"];\n\nconsole.log(fruits.includes(\"банан\")); // true\nconsole.log(fruits.includes(\"груша\")); // false\nconsole.log(fruits.includes(\"банан\", 2)); // false (поиск с индекса 2)","type":"unstyled","key":"6smu2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"3.5 some и every - проверка условия","type":"header-three","key":"cdmjg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8a02u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":34,"style":"ITALIC"},{"length":7,"offset":128,"style":"ITALIC"},{"length":14,"offset":137,"style":"ITALIC"},{"length":8,"offset":223,"style":"ITALIC"},{"length":24,"offset":233,"style":"ITALIC"},{"length":8,"offset":443,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Хотя бы один чётный?\nconst hasEven = numbers.some(n => n % 2 === 0);\nconsole.log(hasEven); // true\n\n// Все чётные?\nconst allEven = numbers.every(n => n % 2 === 0);\nconsole.log(allEven); // false\n\n// Полезно для валидации\nconst users = [\n { name: \"Анна\", age: 25 },\n { name: \"Борис\", age: 17 },\n { name: \"Вика\", age: 30 }\n];\nconst allAdults = users.every(user => user.age >= 18);\nconsole.log(allAdults); // false","type":"unstyled","key":"cnf88"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Методы итерации без трансформации","type":"header-two","key":"41o08"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.1 forEach - просто выполнить","type":"header-three","key":"dr37u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"27l0j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":34,"style":"ITALIC"},{"length":23,"offset":92,"style":"ITALIC"},{"length":26,"offset":173,"style":"ITALIC"},{"length":5,"offset":263,"style":"ITALIC"},{"length":50,"offset":270,"style":"ITALIC"},{"length":54,"offset":367,"style":"ITALIC"},{"length":13,"offset":440,"style":"ITALIC"}],"text":"const numbers = [1, 2, 3, 4, 5];\n\n// Вывод в консоль\nnumbers.forEach(n => console.log(n));\n\n// С доступом к индексу\nnumbers.forEach((n, i) => console.log(`[${i}]: ${n}`));\n\n// Внешний побочный эффект\nlet sum = 0;\nnumbers.forEach(n => sum += n);\nconsole.log(sum); // 15\n\n// Внимание: нельзя break или return (как в цикле)\nnumbers.forEach(n => {\n if (n === 3) return; // только выход из текущей итерации, не из всего цикла\n console.log(n); // 1, 2, 4, 5\n});","type":"unstyled","key":"5dq9t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"4.2 map vs forEach - когда что использовать","type":"header-three","key":"5fnsu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cn4uj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":33,"offset":0,"style":"ITALIC"},{"length":40,"offset":76,"style":"ITALIC"},{"length":51,"offset":156,"style":"ITALIC"},{"length":33,"offset":208,"style":"ITALIC"}],"text":"// map - когда нужен НОВЫЙ массив\nconst doubled = numbers.map(n => n * 2);\n\n// forEach - когда нужен побочный эффект\nnumbers.forEach(n => console.log(n));\n\n// Никогда не используйте map для побочных эффектов\n// Плохо: создаёт ненужный массив\nnumbers.map(n => console.log(n));","type":"unstyled","key":"bp9ri"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. Методы изменения структуры","type":"header-two","key":"9jcpd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.1 flat - разворачивание вложенности","type":"header-three","key":"6skr2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"f8gdm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":35,"offset":75,"style":"ITALIC"},{"length":33,"offset":144,"style":"ITALIC"},{"length":35,"offset":214,"style":"ITALIC"}],"text":"const nested = [1, [2, 3], [4, [5, 6]]];\n\nconsole.log(nested.flat()); // [1, 2, 3, 4, [5, 6]] (глубина 1)\nconsole.log(nested.flat(2)); // [1, 2, 3, 4, 5, 6] (глубина 2)\nconsole.log(nested.flat(Infinity)); // [1, 2, 3, 4, 5, 6] (вся глубина)","type":"unstyled","key":"eaubl"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.2 flatMap - map + flat (глубина 1)","type":"header-three","key":"aa4mj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1ci60"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":31,"offset":0,"style":"ITALIC"},{"length":52,"offset":164,"style":"ITALIC"},{"length":38,"offset":218,"style":"ITALIC"},{"length":36,"offset":392,"style":"ITALIC"},{"length":42,"offset":430,"style":"ITALIC"}],"text":"// Разбить предложения на слова\nconst sentences = [\"Hello world\", \"JavaScript is awesome\"];\nconst words = sentences.flatMap(s => s.split(\" \"));\nconsole.log(words); // [\"Hello\", \"world\", \"JavaScript\", \"is\", \"awesome\"]\n\n// Фильтрация и маппинг за один проход\nconst numbers = [1, 2, 3, 4, 5];\nconst doubledEvens = numbers.flatMap(n => \n n % 2 === 0 ? [n * 2] : []\n);\nconsole.log(doubledEvens); // [4, 8] (только чётные, удвоенные)\n\n// Альтернатива filter + map (два прохода)\nconst doubledEvensOld = numbers.filter(n => n % 2 === 0).map(n => n * 2);","type":"unstyled","key":"j6an"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.3 concat - объединение массивов","type":"header-three","key":"ev3b5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"cc04j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":129,"style":"ITALIC"},{"length":22,"offset":152,"style":"ITALIC"}],"text":"const arr1 = [1, 2];\nconst arr2 = [3, 4];\nconst arr3 = [5, 6];\n\nconst combined = arr1.concat(arr2, arr3);\nconsole.log(combined); // [1, 2, 3, 4, 5, 6]\n\n// Spread-альтернатива\nconst combinedSpread = [...arr1, ...arr2, ...arr3];","type":"unstyled","key":"8u5vv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.4 slice - извлечение части (без мутации)","type":"header-three","key":"eopn3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9r7n7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":61,"style":"ITALIC"},{"length":12,"offset":105,"style":"ITALIC"},{"length":9,"offset":149,"style":"ITALIC"},{"length":26,"offset":190,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\n\nconsole.log(arr.slice(2)); // [3, 4, 5]\nconsole.log(arr.slice(1, 4)); // [2, 3, 4]\nconsole.log(arr.slice(-2)); // [4, 5]\nconsole.log(arr.slice()); // [1, 2, 3, 4, 5] (копия)","type":"unstyled","key":"65aqq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.5 splice - изменение середины (с мутацией)","type":"header-three","key":"32f8j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2kkda"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":11,"offset":30,"style":"ITALIC"},{"length":9,"offset":98,"style":"ITALIC"},{"length":12,"offset":130,"style":"ITALIC"},{"length":10,"offset":144,"style":"ITALIC"},{"length":18,"offset":197,"style":"ITALIC"},{"length":9,"offset":217,"style":"ITALIC"},{"length":20,"offset":271,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\n\n// Удаление\nconst deleted = arr.splice(2, 2);\nconsole.log(deleted); // [3, 4]\nconsole.log(arr); // [1, 2, 5]\n\n// Вставка\narr.splice(2, 0, 3, 4);\nconsole.log(arr); // [1, 2, 3, 4, 5]\n\n// Замена\narr.splice(1, 2, 20, 30);\nconsole.log(arr); // [1, 20, 30, 4, 5]","type":"unstyled","key":"14i5e"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Методы порядка и сортировки","type":"header-two","key":"b2gb7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 sort - сортировка (мутирует!)","type":"header-three","key":"1fc5r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"563q5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":27,"offset":41,"style":"ITALIC"},{"length":35,"offset":107,"style":"ITALIC"},{"length":17,"offset":144,"style":"ITALIC"},{"length":25,"offset":215,"style":"ITALIC"},{"length":14,"offset":242,"style":"ITALIC"},{"length":25,"offset":310,"style":"ITALIC"},{"length":37,"offset":337,"style":"ITALIC"},{"length":49,"offset":499,"style":"ITALIC"},{"length":22,"offset":550,"style":"ITALIC"},{"length":35,"offset":736,"style":"ITALIC"}],"text":"const numbers = [1, 30, 4, 21, 100000];\n\n// Без функции - как строки\nnumbers.sort();\nconsole.log(numbers); // [1, 100000, 21, 30, 4] (НЕ ТАК!)\n\n// По возрастанию\nnumbers.sort((a, b) => a - b);\nconsole.log(numbers); // [1, 4, 21, 30, 100000]\n\n// По убыванию\nnumbers.sort((a, b) => b - a);\nconsole.log(numbers); // [100000, 30, 21, 4, 1]\n\n// Сортировка строк (с учётом локали)\nconst words = [\"réservé\", \"premier\", \"cliché\", \"communiqué\"];\nwords.sort((a, b) => a.localeCompare(b));\nconsole.log(words); // [\"cliché\", \"communiqué\", \"premier\", \"réservé\"]\n\n// Сортировка объектов\nconst users = [\n { name: \"Анна\", age: 30 },\n { name: \"Борис\", age: 25 },\n { name: \"Вика\", age: 35 }\n];\nusers.sort((a, b) => a.age - b.age);\nconsole.log(users); // Борис (25), Анна (30), Вика (35)","type":"unstyled","key":"dp77f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 reverse - обратный порядок (мутирует!)","type":"header-three","key":"ci4c0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"afjap"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":62,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\narr.reverse();\nconsole.log(arr); // [5, 4, 3, 2, 1]","type":"unstyled","key":"aqbdv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.3 toSorted и toReversed (ES2023) - без мутации","type":"header-three","key":"afl6n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"4ft9g"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":66,"style":"ITALIC"},{"length":18,"offset":121,"style":"ITALIC"},{"length":34,"offset":159,"style":"ITALIC"},{"length":23,"offset":195,"style":"ITALIC"},{"length":18,"offset":269,"style":"ITALIC"}],"text":"const arr = [3, 1, 4, 1, 5];\n\nconst sorted = arr.toSorted(); // [1, 1, 3, 4, 5]\nconst reversed = arr.toReversed(); // [5, 1, 4, 1, 3]\n\nconsole.log(arr); // [3, 1, 4, 1, 5] (не изменился!)\n\n// С функцией сравнения\nconst sortedDesc = arr.toSorted((a, b) => b - a); // [5, 4, 3, 1, 1]","type":"unstyled","key":"dj718"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Методы заполнения","type":"header-two","key":"ci62a"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.1 fill - заполнить значением","type":"header-three","key":"2kpra"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fucvq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":57,"style":"ITALIC"},{"length":32,"offset":96,"style":"ITALIC"},{"length":18,"offset":147,"style":"ITALIC"},{"length":30,"offset":167,"style":"ITALIC"},{"length":18,"offset":276,"style":"ITALIC"}],"text":"const arr = new Array(5);\narr.fill(0);\nconsole.log(arr); // [0, 0, 0, 0, 0]\n\narr.fill(1, 2, 4); // с индекса 2 до 4 (не включая)\nconsole.log(arr); // [0, 0, 1, 1, 0]\n\n// Создание последовательности\nconst sequence = new Array(5).fill().map((_, i) => i);\nconsole.log(sequence); // [0, 1, 2, 3, 4]","type":"unstyled","key":"c08ko"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.2 copyWithin - копирование внутри массива","type":"header-three","key":"e5pad"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"acc0d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":72,"style":"ITALIC"},{"length":28,"offset":92,"style":"ITALIC"},{"length":18,"offset":307,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\narr.copyWithin(0, 3, 5);\nconsole.log(arr); // [4, 5, 3, 4, 5]\n\n// Пример: циклический сдвиг\nconst shiftLeft = (arr, n) => {\n const copy = [...arr];\n copy.copyWithin(0, n);\n copy.copyWithin(copy.length - n, 0, n);\n return copy;\n};\nconsole.log(shiftLeft([1, 2, 3, 4, 5], 2)); // [3, 4, 5, 1, 2]","type":"unstyled","key":"25ih6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Методы преобразования в строку","type":"header-two","key":"cb8ac"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.1 join - склеить в строку","type":"header-three","key":"2j3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"995do"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":84,"style":"ITALIC"},{"length":28,"offset":146,"style":"ITALIC"},{"length":30,"offset":210,"style":"ITALIC"},{"length":24,"offset":276,"style":"ITALIC"},{"length":21,"offset":336,"style":"ITALIC"}],"text":"const fruits = [\"яблоко\", \"банан\", \"апельсин\"];\n\nconsole.log(fruits.join()); // \"яблоко,банан,апельсин\"\nconsole.log(fruits.join(\", \")); // \"яблоко, банан, апельсин\"\nconsole.log(fruits.join(\" и \")); // \"яблоко и банан и апельсин\"\nconsole.log(fruits.join(\"\")); // \"яблокобананапельсин\"\nconsole.log([].join(\", \")); // \"\" (пустая строка)","type":"unstyled","key":"cgjl8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"8.2 toString - то же, что join(',')","type":"header-three","key":"3q93m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6ravb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":52,"style":"ITALIC"},{"length":10,"offset":92,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\nconsole.log(arr.toString()); // \"1,2,3\"\nconsole.log(String(arr)); // \"1,2,3\"","type":"unstyled","key":"5cgd4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Новые методы ES2023","type":"header-two","key":"ahncf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.1 toSpliced - splice без мутации","type":"header-three","key":"fk6jq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"58bvs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":96,"style":"ITALIC"},{"length":33,"offset":140,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\nconst newArr = arr.toSpliced(2, 2, 100, 200);\nconsole.log(newArr); // [1, 2, 100, 200, 5]\nconsole.log(arr); // [1, 2, 3, 4, 5] (не изменился)","type":"unstyled","key":"901r2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"9.2 with - замена элемента по индексу","type":"header-three","key":"7s44j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7omsf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":20,"offset":83,"style":"ITALIC"},{"length":33,"offset":125,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\nconst newArr = arr.with(2, 100);\nconsole.log(newArr); // [1, 2, 100, 4, 5]\nconsole.log(arr); // [1, 2, 3, 4, 5] (не изменился)","type":"unstyled","key":"r4eg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Комбинации и цепочки","type":"header-two","key":"1eide"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Сила методов массивов раскрывается в цепочках.","type":"unstyled","key":"74jrc"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"apdnb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":80,"offset":314,"style":"ITALIC"},{"length":18,"offset":466,"style":"ITALIC"},{"length":19,"offset":535,"style":"ITALIC"},{"length":12,"offset":605,"style":"ITALIC"},{"length":14,"offset":668,"style":"ITALIC"},{"length":17,"offset":733,"style":"ITALIC"},{"length":37,"offset":773,"style":"ITALIC"},{"length":31,"offset":812,"style":"ITALIC"}],"text":"const users = [\n { name: \"Анна\", age: 25, city: \"Москва\", active: true },\n { name: \"Борис\", age: 17, city: \"СПб\", active: false },\n { name: \"Вика\", age: 30, city: \"Москва\", active: true },\n { name: \"Глеб\", age: 22, city: \"Казань\", active: true },\n { name: \"Дима\", age: 19, city: \"Москва\", active: false }\n];\n\n// Активные совершеннолетние пользователи из Москвы, отсортированные по возрасту\nconst result = users\n .filter(user => user.active) // только активные\n .filter(user => user.age >= 18) // совершеннолетние\n .filter(user => user.city === \"Москва\") // из Москвы\n .sort((a, b) => a.age - b.age) // по возрасту\n .map(user => `${user.name} (${user.age} лет)`); // форматирование\n\nconsole.log(result); // [\"Анна (25 лет)\", \"Вика (30 лет)\"]\n\n// Статистика в одном выражении\nconst stats = {\n total: users.length,\n active: users.filter(u => u.active).length,\n averageAge: users.reduce((sum, u) => sum + u.age, 0) / users.length,\n cities: [...new Set(users.map(u => u.city))]\n};","type":"unstyled","key":"e56fk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Производительность и оптимизации","type":"header-two","key":"4clng"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3fukr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":0,"style":"ITALIC"},{"length":31,"offset":116,"style":"ITALIC"},{"length":14,"offset":300,"style":"ITALIC"}],"text":"// Плохо: несколько проходов\nconst result = arr\n .filter(x => x > 10)\n .map(x => x * 2)\n .filter(x => x < 100);\n\n// Хорошо: один проход (reduce)\nconst result = arr.reduce((acc, x) => {\n if (x > 10) {\n const doubled = x * 2;\n if (doubled < 100) acc.push(doubled);\n }\n return acc;\n}, []);\n\n// Или flatMap\nconst result = arr.flatMap(x => {\n if (x > 10) {\n const doubled = x * 2;\n return doubled < 100 ? [doubled] : [];\n }\n return [];\n});","type":"unstyled","key":"6l0du"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Полифиллы для понимания","type":"header-two","key":"2sg8n"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2tgad"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":17,"offset":0,"style":"ITALIC"},{"length":20,"offset":179,"style":"ITALIC"},{"length":20,"offset":390,"style":"ITALIC"}],"text":"// Реализация map\nfunction myMap(arr, callback) {\n const result = [];\n for (let i = 0; i < arr.length; i++) {\n result.push(callback(arr[i], i, arr));\n }\n return result;\n}\n\n// Реализация filter\nfunction myFilter(arr, callback) {\n const result = [];\n for (let i = 0; i < arr.length; i++) {\n if (callback(arr[i], i, arr)) {\n result.push(arr[i]);\n }\n }\n return result;\n}\n\n// Реализация reduce\nfunction myReduce(arr, callback, initialValue) {\n let accumulator = initialValue;\n let startIndex = 0;\n \n if (accumulator === undefined) {\n accumulator = arr[0];\n startIndex = 1;\n }\n \n for (let i = startIndex; i < arr.length; i++) {\n accumulator = callback(accumulator, arr[i], i, arr);\n }\n \n return accumulator;\n}","type":"unstyled","key":"14ov6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Шпаргалка методов","type":"header-two","key":"3q0l8"},{"data":{"image":{"id":"69db737aec32b11c51b60ba0"}},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"atomic:image","key":"ebf5s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"fa2sb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":0,"style":"BOLD"}],"text":"Финальный тест (что выведет?):","type":"unstyled","key":"bo1qq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"tq9c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"const arr = [1, 2, 3, 4, 5];\n\nconsole.log(arr.map(n => n * 2));\nconsole.log(arr.filter(n => n % 2 === 0));\nconsole.log(arr.reduce((a, b) => a + b, 0));\nconsole.log(arr.find(n => n > 3));\nconsole.log(arr.some(n => n > 10));\nconsole.log(arr.every(n => n > 0));\nconsole.log(arr.slice(1, 4));\nconsole.log(arr.sort((a, b) => b - a));","type":"unstyled","key":"95rga"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":0,"style":"BOLD"}],"text":"Ответы: [2,4,6,8,10], [2,4], 15, 4, false, true, [2,3,4], [5,4,3,2,1] (массив изменился).","type":"unstyled","key":"40p9f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Методы массивов - это не просто инструменты. Это язык, на котором вы говорите с данными. Чем лучше вы его знаете, тем элегантнее становятся ваши решения. Изучите их, практикуйтесь, комбинируйте. И однажды вы поймёте, что циклы вам больше почти не нужны. А это - настоящая свобода.","type":"unstyled","key":"d2v50"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"8rb88"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"------------------------------------------------------------------------------------------","type":"unstyled","key":"1bgvk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"------------------------------------------------------------------------------------------","type":"unstyled","key":"1rvh7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Путешественники вселенной: Итераторы, перебираемые объекты и магия for...of","type":"header-two","key":"303pv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Представьте, что вы можете пройтись по любой структуре данных одним и тем же способом. По массиву - for...of. По строке - for...of. По множеству, словарю, генератору - снова for...of. Даже по своей собственной, с нуля написанной структуре данных.","type":"unstyled","key":"251gg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Это не магия. Это протокол итерации - один из самых элегантных механизмов в JavaScript.","type":"unstyled","key":"6gj7f"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Перебираемые объекты (iterables) - это стандартный интерфейс, который позволяет любому объекту стать \"перебираемым\". А итераторы - это механизм, который управляет этим перебором.","type":"unstyled","key":"3b2c"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Сегодня мы разберём, как устроена эта механика, как создавать свои итерируемые объекты и как использовать мощь итераторов для ленивых вычислений.","type":"unstyled","key":"92o3v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 1. Что такое перебираемый объект?","type":"header-two","key":"5ffk3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":0,"style":"BOLD"}],"text":"Перебираемый объект (iterable) - это любой объект, который умеет возвращать итератор. Встроенные перебираемые объекты: массивы, строки, Map, Set, arguments, DOM-коллекции (NodeList).","type":"unstyled","key":"9k4au"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"8l56o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":24,"offset":0,"style":"ITALIC"},{"length":10,"offset":95,"style":"ITALIC"},{"length":24,"offset":109,"style":"ITALIC"},{"length":16,"offset":202,"style":"ITALIC"},{"length":21,"offset":222,"style":"ITALIC"},{"length":10,"offset":325,"style":"ITALIC"},{"length":52,"offset":339,"style":"ITALIC"},{"length":11,"offset":496,"style":"ITALIC"}],"text":"// Массив - перебираемый\nconst arr = [1, 2, 3];\nfor (const item of arr) {\n console.log(item); // 1, 2, 3\n}\n\n// Строка - перебираемая\nconst str = \"hello\";\nfor (const char of str) {\n console.log(char); // h, e, l, l, o\n}\n\n// Set - перебираемый\nconst set = new Set([1, 2, 3]);\nfor (const value of set) {\n console.log(value); // 1, 2, 3\n}\n\n// Map - перебираемый (возвращает пары [key, value])\nconst map = new Map([[\"a\", 1], [\"b\", 2]]);\nfor (const [key, value] of map) {\n console.log(key, value); // a 1, b 2\n}","type":"unstyled","key":"3h2p2"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 2. for...of - король перебора","type":"header-two","key":"2o95v"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"for...of - это современный способ перебора перебираемых объектов.","type":"unstyled","key":"1gels"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"qnvi"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":31,"offset":27,"style":"ITALIC"},{"length":13,"offset":108,"style":"ITALIC"},{"length":50,"offset":125,"style":"ITALIC"},{"length":16,"offset":221,"style":"ITALIC"},{"length":50,"offset":241,"style":"ITALIC"},{"length":16,"offset":358,"style":"ITALIC"}],"text":"const arr = [10, 20, 30];\n\n// for...of перебирает значения\nfor (const value of arr) {\n console.log(value); // 10, 20, 30\n}\n\n// В отличие от for...in, который перебирает ключи\nfor (const key in arr) {\n console.log(key); // \"0\", \"1\", \"2\"\n}\n\n// for...of работает с любым перебираемым объектом\nconst str = \"abc\";\nfor (const char of str) {\n console.log(char); // \"a\", \"b\", \"c\"\n}","type":"unstyled","key":"2ujic"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 3. Что такое итератор?","type":"header-two","key":"2br84"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":0,"style":"BOLD"}],"text":"Итератор (iterator) - это объект с методом next(), который возвращает объект { value, done }.","type":"unstyled","key":"6f9g6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"97s5p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":0,"style":"ITALIC"},{"length":28,"offset":278,"style":"ITALIC"},{"length":28,"offset":343,"style":"ITALIC"},{"length":28,"offset":408,"style":"ITALIC"},{"length":28,"offset":473,"style":"ITALIC"},{"length":35,"offset":538,"style":"ITALIC"}],"text":"// Создадим простой итератор\nconst simpleIterator = {\n current: 0,\n last: 3,\n \n next() {\n if (this.current <= this.last) {\n return { value: this.current++, done: false };\n }\n return { value: undefined, done: true };\n }\n};\n\nconsole.log(simpleIterator.next()); // { value: 0, done: false }\nconsole.log(simpleIterator.next()); // { value: 1, done: false }\nconsole.log(simpleIterator.next()); // { value: 2, done: false }\nconsole.log(simpleIterator.next()); // { value: 3, done: false }\nconsole.log(simpleIterator.next()); // { value: undefined, done: true }","type":"unstyled","key":"d1d4u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 4. Протокол итерации","type":"header-two","key":"b1i2b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Протокол итерации состоит из двух частей:","type":"unstyled","key":"c33il"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"}],"text":"Iterable - объект, у которого есть метод [Symbol.iterator](), возвращающий итератор.","type":"ordered-list-item","key":"7qrgs"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"}],"text":"Iterator - объект с методом next(), возвращающим { value, done }.","type":"ordered-list-item","key":"17p6j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"831ct"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":40,"offset":0,"style":"ITALIC"},{"length":38,"offset":82,"style":"ITALIC"},{"length":22,"offset":209,"style":"ITALIC"},{"length":48,"offset":425,"style":"ITALIC"},{"length":16,"offset":521,"style":"ITALIC"},{"length":17,"offset":541,"style":"ITALIC"},{"length":18,"offset":609,"style":"ITALIC"}],"text":"// Объект, реализующий протокол итерации\nconst range = {\n from: 1,\n to: 5,\n \n // Метод, делающий объект перебираемым\n [Symbol.iterator]() {\n let current = this.from;\n const last = this.to;\n \n // Возвращаем итератор\n return {\n next() {\n if (current <= last) {\n return { value: current++, done: false };\n }\n return { value: undefined, done: true };\n }\n };\n }\n};\n\n// Теперь range можно перебирать через for...of!\nfor (const num of range) {\n console.log(num); // 1, 2, 3, 4, 5\n}\n\n// И через spread\nconst numbers = [...range];\nconsole.log(numbers); // [1, 2, 3, 4, 5]","type":"unstyled","key":"41k7h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 5. Встроенные перебираемые объекты","type":"header-two","key":"788fh"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.1 Массивы","type":"header-three","key":"fjps5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3ncnb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":24,"style":"ITALIC"},{"length":28,"offset":118,"style":"ITALIC"},{"length":28,"offset":177,"style":"ITALIC"},{"length":28,"offset":236,"style":"ITALIC"},{"length":35,"offset":295,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\n\n// Получение итератора\nconst iterator = arr[Symbol.iterator]();\nconsole.log(iterator.next()); // { value: 1, done: false }\nconsole.log(iterator.next()); // { value: 2, done: false }\nconsole.log(iterator.next()); // { value: 3, done: false }\nconsole.log(iterator.next()); // { value: undefined, done: true }","type":"unstyled","key":"f1030"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.2 Строки (работают с эмодзи правильно!)","type":"header-three","key":"65gjv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bto74"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":70,"style":"ITALIC"},{"length":21,"offset":93,"style":"ITALIC"},{"length":42,"offset":160,"style":"ITALIC"}],"text":"const str = \"hello\uD83D\uDE0A\";\n\nfor (const char of str) {\n console.log(char); // h, e, l, l, o, \uD83D\uDE0A\n}\n\n// Разница с for...in\nfor (const key in str) {\n console.log(key); // 0, 1, 2, 3, 4, 5 (индексы, не символы!)\n}","type":"unstyled","key":"5nqa7"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.3 Map (возвращает пары)","type":"header-three","key":"did68"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3jchn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":122,"style":"ITALIC"},{"length":35,"offset":152,"style":"ITALIC"},{"length":18,"offset":216,"style":"ITALIC"},{"length":20,"offset":264,"style":"ITALIC"},{"length":51,"offset":316,"style":"ITALIC"}],"text":"const map = new Map([\n [\"name\", \"Анна\"],\n [\"age\", 25]\n]);\n\nfor (const [key, value] of map) {\n console.log(key, value); // \"name\" \"Анна\", \"age\" 25\n}\n\n// Можно получить итератор отдельно\nconst keys = map.keys(); // итератор ключей\nconst values = map.values(); // итератор значений\nconst entries = map.entries(); // итератор пар (то же, что map[Symbol.iterator]())","type":"unstyled","key":"3ao5p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.4 Set (возвращает значения)","type":"header-three","key":"37u9u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"hgm6"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":82,"style":"ITALIC"}],"text":"const set = new Set([1, 2, 3]);\n\nfor (const value of set) {\n console.log(value); // 1, 2, 3\n}","type":"unstyled","key":"2ec9m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.5 arguments (псевдомассив)","type":"header-three","key":"97ft5"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"adlh4"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":5,"offset":138,"style":"ITALIC"}],"text":"function sum() {\n let total = 0;\n for (const num of arguments) {\n total += num;\n }\n return total;\n}\n\nconsole.log(sum(1, 2, 3, 4)); // 10","type":"unstyled","key":"6gt80"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"5.6 NodeList (DOM-коллекции)","type":"header-three","key":"bevf0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"qklj"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":23,"offset":109,"style":"ITALIC"}],"text":"const divs = document.querySelectorAll('div');\n\nfor (const div of divs) {\n console.log(div.textContent);\n}\n\n// Превращение в массив\nconst divsArray = [...divs];","type":"unstyled","key":"6njsn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 6. Создание своих перебираемых объектов","type":"header-two","key":"dnmk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.1 Диапазон чисел","type":"header-three","key":"a92mf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"91alu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":542,"style":"ITALIC"}],"text":"class Range {\n constructor(start, end, step = 1) {\n this.start = start;\n this.end = end;\n this.step = step;\n }\n \n [Symbol.iterator]() {\n let current = this.start;\n const end = this.end;\n const step = this.step;\n \n return {\n next() {\n if (current <= end) {\n const value = current;\n current += step;\n return { value, done: false };\n }\n return { value: undefined, done: true };\n }\n };\n }\n}\n\nconst numbers = new Range(1, 10, 2);\nconsole.log([...numbers]); // [1, 3, 5, 7, 9]","type":"unstyled","key":"4vd02"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.2 Бесконечная последовательность (Фибоначчи)","type":"header-three","key":"3qa6d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2df04"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":25,"offset":224,"style":"ITALIC"},{"length":24,"offset":273,"style":"ITALIC"},{"length":37,"offset":429,"style":"ITALIC"}],"text":"const fibonacci = {\n [Symbol.iterator]() {\n let prev = 0;\n let curr = 1;\n \n return {\n next() {\n const value = curr;\n [prev, curr] = [curr, prev + curr];\n return { value, done: false }; // никогда не закончится!\n }\n };\n }\n};\n\n// Берём первые 10 чисел\nconst first10 = [];\nlet i = 0;\nfor (const num of fibonacci) {\n if (i++ >= 10) break;\n first10.push(num);\n}\nconsole.log(first10); // [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]","type":"unstyled","key":"f5tc3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"6.3 Перебор объекта (по значениям)","type":"header-three","key":"d57fg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"3jqbg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":42,"offset":35,"style":"ITALIC"},{"length":44,"offset":78,"style":"ITALIC"},{"length":27,"offset":124,"style":"ITALIC"},{"length":68,"offset":449,"style":"ITALIC"},{"length":10,"offset":567,"style":"ITALIC"},{"length":27,"offset":581,"style":"ITALIC"},{"length":10,"offset":988,"style":"ITALIC"}],"text":"const obj = { a: 1, b: 2, c: 3 };\n\n// Обычный объект не является перебираемым\n// for (const value of obj) {} // TypeError!\n\n// Сделаем его перебираемым\nObject.prototype[Symbol.iterator] = function() {\n const values = Object.values(this);\n let index = 0;\n \n return {\n next: () => {\n if (index < values.length) {\n return { value: values[index++], done: false };\n }\n return { value: undefined, done: true };\n }\n };\n};\n\n// Теперь работает (но лучше так не делать — загрязнение прототипа!)\nfor (const value of obj) {\n console.log(value); // 1, 2, 3\n}\n\n// Лучше: отдельная функция\nfunction objectIterator(obj) {\n const values = Object.values(obj);\n let index = 0;\n \n return {\n [Symbol.iterator]() { return this; },\n next() {\n if (index < values.length) {\n return { value: values[index++], done: false };\n }\n return { value: undefined, done: true };\n }\n };\n}\n\nfor (const value of objectIterator(obj)) {\n console.log(value); // 1, 2, 3\n}","type":"unstyled","key":"3j3jn"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 7. Итераторы вручную","type":"header-two","key":"2p3ji"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.1 Создание итератора без объекта","type":"header-three","key":"8ba7b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"7rg3j"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":28,"offset":297,"style":"ITALIC"},{"length":28,"offset":352,"style":"ITALIC"},{"length":28,"offset":407,"style":"ITALIC"},{"length":35,"offset":462,"style":"ITALIC"}],"text":"function makeIterator(array) {\n let index = 0;\n \n return {\n next() {\n if (index < array.length) {\n return { value: array[index++], done: false };\n }\n return { value: undefined, done: true };\n }\n };\n}\n\nconst iter = makeIterator([1, 2, 3]);\nconsole.log(iter.next()); // { value: 1, done: false }\nconsole.log(iter.next()); // { value: 2, done: false }\nconsole.log(iter.next()); // { value: 3, done: false }\nconsole.log(iter.next()); // { value: undefined, done: true }","type":"unstyled","key":"fkr0o"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"7.2 Итератор, который можно использовать в for...of","type":"header-three","key":"eslto"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Чтобы итератор работал с for...of, он должен сам быть перебираемым (иметь [Symbol.iterator], возвращающий себя).","type":"unstyled","key":"ct1ud"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"2v974"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":10,"offset":385,"style":"ITALIC"}],"text":"function createIterable(array) {\n let index = 0;\n \n return {\n [Symbol.iterator]() {\n return this;\n },\n next() {\n if (index < array.length) {\n return { value: array[index++], done: false };\n }\n return { value: undefined, done: true };\n }\n };\n}\n\nconst iterable = createIterable([1, 2, 3]);\nfor (const value of iterable) {\n console.log(value); // 1, 2, 3\n}","type":"unstyled","key":"32cvf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 8. Ленивые вычисления через итераторы","type":"header-two","key":"7cjas"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Главная суперсила итераторов - ленивость. Значения вычисляются только тогда, когда они нужны.","type":"unstyled","key":"ab1u1"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"fofdm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":39,"offset":0,"style":"ITALIC"},{"length":23,"offset":193,"style":"ITALIC"},{"length":20,"offset":367,"style":"ITALIC"},{"length":83,"offset":389,"style":"ITALIC"},{"length":47,"offset":473,"style":"ITALIC"}],"text":"// Бесконечный итератор случайных чисел\nconst randomNumbers = {\n [Symbol.iterator]() {\n return {\n next() {\n return { value: Math.random(), done: false };\n }\n };\n }\n};\n\n// Берём только 5 чисел\nconst fiveRandoms = [];\nfor (const num of randomNumbers) {\n if (fiveRandoms.length >= 5) break;\n fiveRandoms.push(num);\n}\nconsole.log(fiveRandoms); // 5 случайных чисел\n\n// А если бы мы создали массив из 1000000 случайных чисел - память бы переполнилась\n// С итератором мы берём столько, сколько нужно","type":"unstyled","key":"3ga4k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 9. Spread и деструктуризация с итераторами","type":"header-two","key":"50e7p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"... (spread) и деструктуризация массива работают с любыми перебираемыми объектами.","type":"unstyled","key":"bd80d"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"a08cm"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":9,"offset":308,"style":"ITALIC"},{"length":18,"offset":360,"style":"ITALIC"},{"length":19,"offset":380,"style":"ITALIC"},{"length":18,"offset":474,"style":"ITALIC"},{"length":13,"offset":494,"style":"ITALIC"},{"length":18,"offset":559,"style":"ITALIC"}],"text":"const range = {\n from: 1,\n to: 5,\n [Symbol.iterator]() {\n let current = this.from;\n const last = this.to;\n return {\n next() {\n if (current <= last) {\n return { value: current++, done: false };\n }\n return { value: undefined, done: true };\n }\n };\n }\n};\n\n// Spread\nconst arr = [...range];\nconsole.log(arr); // [1, 2, 3, 4, 5]\n\n// Деструктуризация\nconst [first, second, ...rest] = range;\nconsole.log(first, second, rest); // 1, 2, [3, 4, 5]\n\n// Array.from\nconst arr2 = Array.from(range);\nconsole.log(arr2); // [1, 2, 3, 4, 5]","type":"unstyled","key":"d3a7h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 10. Генераторы - фабрики итераторов","type":"header-two","key":"bnaqd"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Генераторы — это удобный способ создания итераторов. Мы подробно разберём их в отдельной статье, но базовое понимание важно.","type":"unstyled","key":"5cnmu"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"6rldr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":51,"offset":0,"style":"ITALIC"},{"length":18,"offset":213,"style":"ITALIC"},{"length":47,"offset":233,"style":"ITALIC"},{"length":4,"offset":476,"style":"ITALIC"},{"length":4,"offset":512,"style":"ITALIC"},{"length":4,"offset":548,"style":"ITALIC"},{"length":4,"offset":584,"style":"ITALIC"},{"length":4,"offset":620,"style":"ITALIC"}],"text":"// Генератор - функция, которая возвращает итератор\nfunction* range(start, end, step = 1) {\n for (let i = start; i <= end; i += step) {\n yield i;\n }\n}\n\nconst numbers = range(1, 5);\nconsole.log([...numbers]); // [1, 2, 3, 4, 5]\n\n// Генератор для бесконечной последовательности\nfunction* fibonacci() {\n let prev = 0;\n let curr = 1;\n \n while (true) {\n yield curr;\n [prev, curr] = [curr, prev + curr];\n }\n}\n\nconst fib = fibonacci();\nconsole.log(fib.next().value); // 1\nconsole.log(fib.next().value); // 1\nconsole.log(fib.next().value); // 2\nconsole.log(fib.next().value); // 3\nconsole.log(fib.next().value); // 5","type":"unstyled","key":"bjntf"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 11. Проверка на перебираемость","type":"header-two","key":"fe0b"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9tu55"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":7,"offset":138,"style":"ITALIC"},{"length":7,"offset":186,"style":"ITALIC"},{"length":7,"offset":235,"style":"ITALIC"},{"length":7,"offset":284,"style":"ITALIC"},{"length":8,"offset":333,"style":"ITALIC"},{"length":8,"offset":383,"style":"ITALIC"},{"length":8,"offset":433,"style":"ITALIC"}],"text":"function isIterable(obj) {\n return obj != null && typeof obj[Symbol.iterator] === 'function';\n}\n\nconsole.log(isIterable([1, 2, 3])); // true\nconsole.log(isIterable(\"hello\")); // true\nconsole.log(isIterable(new Map())); // true\nconsole.log(isIterable(new Set())); // true\nconsole.log(isIterable({})); // false\nconsole.log(isIterable(null)); // false\nconsole.log(isIterable(42)); // false","type":"unstyled","key":"n12h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 12. Реальные кейсы","type":"header-two","key":"4vrg9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"12.1 Пагинация через итератор","type":"header-three","key":"2e5si"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"bspq3"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":16,"offset":346,"style":"ITALIC"},{"length":21,"offset":490,"style":"ITALIC"}],"text":"async function* paginatedFetch(url, pageSize = 10) {\n let page = 1;\n let hasMore = true;\n \n while (hasMore) {\n const response = await fetch(`${url}?_page=${page}&_limit=${pageSize}`);\n const data = await response.json();\n \n if (data.length === 0) {\n hasMore = false;\n } else {\n yield data;\n page++;\n }\n }\n}\n\n// Использование\nfor await (const page of paginatedFetch('/api/users')) {\n console.log(`Получена страница с ${page.length} пользователями`);\n // Обработка страницы\n}","type":"unstyled","key":"b4foe"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"12.2 Обработка больших файлов","type":"header-three","key":"fa4jb"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"d7p3r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"function* chunkReader(string, chunkSize = 100) {\n for (let i = 0; i < string.length; i += chunkSize) {\n yield string.slice(i, i + chunkSize);\n }\n}\n\nconst hugeString = \"x\".repeat(1000000);\nlet processed = 0;\n\nfor (const chunk of chunkReader(hugeString, 1000)) {\n processChunk(chunk);\n processed += chunk.length;\n console.log(`Обработано: ${processed} символов`);\n}","type":"unstyled","key":"5cf5k"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"12.3 Древовидный обход (DFS)","type":"header-three","key":"46u0t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"qetg"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":22,"offset":393,"style":"ITALIC"}],"text":"function* traverseTree(node) {\n yield node.value;\n \n if (node.children) {\n for (const child of node.children) {\n yield* traverseTree(child);\n }\n }\n}\n\nconst tree = {\n value: 1,\n children: [\n { value: 2, children: [{ value: 4 }, { value: 5 }] },\n { value: 3, children: [{ value: 6 }, { value: 7 }] }\n ]\n};\n\nfor (const value of traverseTree(tree)) {\n console.log(value); // 1, 2, 4, 5, 3, 6, 7\n}","type":"unstyled","key":"4qlso"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Часть 13. Подводные камни","type":"header-two","key":"5r3u"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #1: Объекты не перебираемы по умолчанию","type":"header-three","key":"c2s5t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"9hm16"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":13,"offset":56,"style":"ITALIC"},{"length":38,"offset":71,"style":"ITALIC"}],"text":"const obj = { a: 1, b: 2 };\nfor (const value of obj) {} // TypeError!\n\n// Решение: использовать Object.values\nfor (const value of Object.values(obj)) {}","type":"unstyled","key":"fji2t"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #2: Нельзя прервать forEach, но можно прервать for...of","type":"header-three","key":"74bju"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"b4huk"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":26,"offset":30,"style":"ITALIC"},{"length":15,"offset":98,"style":"ITALIC"},{"length":17,"offset":119,"style":"ITALIC"},{"length":11,"offset":182,"style":"ITALIC"}],"text":"const arr = [1, 2, 3, 4, 5];\n\n// forEach нельзя прервать\narr.forEach(n => {\n if (n === 3) break; // SyntaxError!\n});\n\n// for...of можно\nfor (const n of arr) {\n if (n === 3) break; // работает\n}","type":"unstyled","key":"cd494"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Камень #3: Итераторы одноразовые","type":"header-three","key":"facjr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"1n7he"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":85,"style":"ITALIC"},{"length":32,"offset":122,"style":"ITALIC"}],"text":"const arr = [1, 2, 3];\nconst iter = arr[Symbol.iterator]();\n\nconsole.log([...iter]); // [1, 2, 3]\nconsole.log([...iter]); // [] (пусто! итератор исчерпан)","type":"unstyled","key":"ag9du"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итог: Манифест итераторов","type":"header-two","key":"81lq0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":19,"offset":0,"style":"BOLD"}],"text":"Перебираемый объект имеет метод [Symbol.iterator](), возвращающий итератор.","type":"ordered-list-item","key":"cf2vr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"}],"text":"Итератор имеет метод next(), возвращающий { value, done }.","type":"ordered-list-item","key":"jm1m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"for...of - универсальный способ перебора перебираемых объектов.","type":"ordered-list-item","key":"77ne9"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":46,"offset":0,"style":"BOLD"}],"text":"Массивы, строки, Map, Set, arguments, NodeList - встроенные перебираемые объекты.","type":"ordered-list-item","key":"4a8q8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":8,"offset":0,"style":"BOLD"},{"length":20,"offset":11,"style":"BOLD"}],"text":"Spread (...) и деструктуризация работают с любыми перебираемыми объектами.","type":"ordered-list-item","key":"29cu0"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":12,"offset":0,"style":"BOLD"},{"length":1,"offset":21,"style":"BOLD"}],"text":"Генераторы (function*) - удобный способ создания итераторов.","type":"ordered-list-item","key":"3sa9m"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":18,"offset":0,"style":"BOLD"}],"text":"Ленивые вычисления - главная суперсила итераторов (бесконечные последовательности).","type":"ordered-list-item","key":"8nblv"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":21,"offset":0,"style":"BOLD"}],"text":"Итераторы одноразовые - после прохода их нельзя использовать снова.","type":"ordered-list-item","key":"1aj2h"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":30,"offset":0,"style":"BOLD"}],"text":"Финальный тест (что выведет?):","type":"unstyled","key":"9rut8"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"javascript","type":"unstyled","key":"67mid"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"const range = {\n from: 1,\n to: 3,\n [Symbol.iterator]() {\n let current = this.from;\n const last = this.to;\n return {\n next() {\n if (current <= last) {\n return { value: current++, done: false };\n }\n return { value: undefined, done: true };\n }\n };\n }\n};\n\nconsole.log([...range]);\nconsole.log([...range]);\n\nfor (const num of range) {\n console.log(num);\n}\n\nconst [first, second] = range;\nconsole.log(first, second);","type":"unstyled","key":"amr6s"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[{"length":6,"offset":0,"style":"BOLD"}],"text":"Ответ: [1, 2, 3], [1, 2, 3] (каждый раз новый итератор), 1 2 3, 1 2.","type":"unstyled","key":"7efsr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"Итераторы и перебираемые объекты - это мост между данными и их обработкой. Они позволяют абстрагироваться от структуры данных и работать с ними единообразно. А возможность создавать свои итераторы открывает дверь в мир ленивых вычислений и эффективной обработки больших данных. Освойте этот механизм, и ваш код станет гибче и выразительнее.","type":"unstyled","key":"a2vga"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"3dpol"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"1q69p"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"34pop"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"3pldq"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"70f3r"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"unstyled","key":"cpbvr"},{"data":{},"depth":0,"entityRanges":[],"inlineStyleRanges":[],"text":"","type":"marker","key":"daKhKhzhIj0icw32hvBv"}],"entityMap":{}},"mentions":[]}