61 lines
1.3 KiB
Markdown
61 lines
1.3 KiB
Markdown
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---
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title: Reuse Patterns Using Capture Groups
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localeTitle: 使用捕获组重用模式
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---
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## 使用Capture Group重用模式
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## 提示1：
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给出以下代码：
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```javascript
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let testString = "test test test ";
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let reRegex =/(test)\s\1/;
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let result = reRegex.test(testString);
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```
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`result`将仅匹配`test test`因为此示例中的`\1`代表与最近匹配的第一个捕获组`(test)`相同的文本。
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如果我们要正面翻译正则表达式，它看起来像这样：
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```js
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let re = /(test)\s\1;
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let literalRe = /test\stest;
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```
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`rea`和`literalRe`都会匹配相同的东西。
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## 提示2：
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鉴于以下代码：
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```javascript
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let testString = "test test test ";
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let reRegex =/(test)(\s)\1\2\1/;
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let result = reRegex.test(testString);
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```
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将匹配整个`test test test`因为： `\1`重复（测试） `\2`重复（\\ s）
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## 提示3：
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代码如下：
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```javascript
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let testString = "test test test test test test";
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let reRegex =/(test)(\s)\1\2\1/g;
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let result = reRegex.test(testString);
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```
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因为我们使用了`\g` ，我们的正则表达式在第一次完全匹配（ `test test test` ）之后没有返回并匹配所有重复。
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## 剧透警报 - 提前解决！
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## 解：
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```javascript
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let repeatNum = "42 42 42";
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let reRegex = /^(\d+)\s\1\s\1$/;
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let result = reRegex.test(repeatNum);
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```
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