---
id: a0b5010f579e69b815e7c5d6
title: Search and Replace
isRequired: true
challengeType: 5
videoUrl: ''
localeTitle: 搜索和替换
---
## Description
使用提供的参数执行搜索并替换句子并返回新句子。第一个参数是执行搜索和替换的句子。第二个参数是你要替换的词（之前）。第三个参数是你将用（后）替换第二个参数。 注意
在更换原始单词时保留原始单词中第一个字符的大小写。例如，如果您的意思是将“Book”替换为“dog”，则应将其替换为“Dog”。如果卡住，请记住使用Read-Search-Ask 。尝试配对程序。编写自己的代码。
## Instructions
## Tests
```yml
tests:
- text: 'myReplace("Let us go to the store", "store", "mall")应该返回“让我们去商场”。'
testString: assert.deepEqual(myReplace("Let us go to the store", "store", "mall"), "Let us go to the mall");
- text: 'myReplace("He is Sleeping on the couch", "Sleeping", "sitting")应该回归“他正坐在沙发上”。'
testString: assert.deepEqual(myReplace("He is Sleeping on the couch", "Sleeping", "sitting"), "He is Sitting on the couch");
- text: 'myReplace("This has a spellngi error", "spellngi", "spelling")应该返回“这有一个拼写错误”。'
testString: assert.deepEqual(myReplace("This has a spellngi error", "spellngi", "spelling"), "This has a spelling error");
- text: 'myReplace("His name is Tom", "Tom", "john")应该回归“他的名字是约翰”。'
testString: assert.deepEqual(myReplace("His name is Tom", "Tom", "john"), "His name is John");
- text: 'myReplace("Let us get back to more Coding", "Coding", "algorithms")应该返回“让我们回到更多算法”。'
testString: assert.deepEqual(myReplace("Let us get back to more Coding", "Coding", "algorithms"), "Let us get back to more Algorithms");
```
## Challenge Seed
```js
function myReplace(str, before, after) {
return str;
}
myReplace("A quick brown fox jumped over the lazy dog", "jumped", "leaped");
```
## Solution
```js
// solution required
```