46 lines
1.4 KiB
Markdown
46 lines
1.4 KiB
Markdown
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---
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title: Refactor Global Variables Out of Functions
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localeTitle: 重构函数的全局变量
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---
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## 重构函数的全局变量
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* 如果您在更改bookList时遇到问题，请尝试在函数中使用该数组的副本。
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* 这里有一些关于\[JavaScript如何处理函数参数\]的更多信息（https://codeburst.io/javascript-passing-by-value-vs- reference-explanation-in-plain-english-8d00fd06a47c）。
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## 基本代码解决方案
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## 解决方案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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## 解决方案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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