42 lines
1.3 KiB
Markdown
42 lines
1.3 KiB
Markdown
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---
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title: Refactor Global Variables Out of Functions
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---
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## Refactor Global Variables Out of Functions
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- If you're having trouble with changing bookList, try using a copy of the array in your functions.
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- Here's some more information about [how JavaScript handles function arguments](https://codeburst.io/javascript-passing-by-value-vs- reference-explained-in-plain-english-8d00fd06a47c).
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## ![:beginner:](https://forum.freecodecamp.com/images/emoji/emoji_one/beginner.png?v=3 ":beginner:") Basic Code Solution:
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## Solution 1
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```javascript
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function add (arr, bookName) {
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let newArr = [...arr]; // Copy the bookList array to a new array.
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newArr.push(bookName); // Add bookName parameter to the end of the new array.
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return newArr; // Return the new array.
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}
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function remove (arr, bookName) {
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let newArr = [...arr]; // Copy the bookList array to a new array.
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if (newArr.indexOf(bookName) >= 0) { // Check whether the bookName parameter is in new array.
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/.
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newArr.splice(newArr.indexOf(bookName), 1); // Remove the given paramater from the new array.
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return newArr; // Return the new array.
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}
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}
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```
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## Solution 2
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```javascript
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function add (list,bookName) {
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return [...list, bookName];
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}
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function remove (list,bookName) {
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if (list.indexOf(bookName) >= 0) {
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return list.filter((item) => item !== bookName);
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}
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}
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```
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