87 lines
6.5 KiB
Markdown
87 lines
6.5 KiB
Markdown
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---
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id: 587d7b8f367417b2b2512b60
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title: Refactor Global Variables Out of Functions
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challengeType: 1
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videoUrl: ''
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localeTitle: Глобальные переменные Refactor вне функций
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---
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## Description
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<section id="description"> До сих пор мы видели два разных принципа функционального программирования: 1) Не изменяйте переменную или объект - создавайте новые переменные и объекты и возвращайте их, если необходимо, из функции. 2) Объявлять аргументы функции - любое вычисление внутри функции зависит только от аргументов, а не от любого глобального объекта или переменной. Добавление одного к числу не очень интересно, но мы можем применять эти принципы при работе с массивами или более сложными объектами. </section>
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## Instructions
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<section id="instructions"> Refactor (переписать) код, поэтому глобальный массив <code>bookList</code> не изменяется внутри любой функции. Функция <code>add</code> должна добавить данное имя <code>bookName</code> в конец массива. Функция <code>remove</code> должна удалить данную <code>bookName</code> из массива. Обе функции должны возвращать массив, и любые новые параметры должны быть добавлены до имени <code>bookName</code> . </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: '<code>bookList</code> не должен меняться и <code>bookList</code> равным <code>["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]</code> .'
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testString: 'assert(JSON.stringify(bookList) === JSON.stringify(["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]), "<code>bookList</code> should not change and still equal <code>["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]</code>.");'
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- text: '<code>newBookList</code> должен равняться <code>["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code> <code>newBookList</code> <code>["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code> .'
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testString: 'assert(JSON.stringify(newBookList) === JSON.stringify(["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]), "<code>newBookList</code> should equal <code>["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code>.");'
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- text: '<code>newerBookList</code> должен равняться <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]</code> <code>newerBookList</code> <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]</code> .'
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testString: 'assert(JSON.stringify(newerBookList) === JSON.stringify(["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]), "<code>newerBookList</code> should equal <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"]</code>.");'
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- text: '<code>newestBookList</code> должен равняться <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code> <code>newestBookList</code> <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code> .'
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testString: 'assert(JSON.stringify(newestBookList) === JSON.stringify(["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]), "<code>newestBookList</code> should equal <code>["The Hound of the Baskervilles", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae", "A Brief History of Time"]</code>.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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// the global variable
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var bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];
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/* This function should add a book to the list and return the list */
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// New parameters should come before the bookName one
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// Add your code below this line
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function add (bookName) {
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return bookList.push(bookName);
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// Add your code above this line
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}
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/* This function should remove a book from the list and return the list */
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// New parameters should come before the bookName one
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// Add your code below this line
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function remove (bookName) {
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if (bookList.indexOf(bookName) >= 0) {
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return bookList.splice(0, 1, bookName);
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// Add your code above this line
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}
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}
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var newBookList = add(bookList, 'A Brief History of Time');
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var newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
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var newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');
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console.log(bookList);
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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