---
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", "myReplace("Let us go to the store", "store", "mall") should return "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", "myReplace("He is Sleeping on the couch", "Sleeping", "sitting") should return "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", "myReplace("This has a spellngi error", "spellngi", "spelling") should return "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", "myReplace("His name is Tom", "Tom", "john") should return "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", "myReplace("Let us get back to more Coding", "Coding", "algorithms") should return "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
```