regular expression rules 正则表达式
正则表达式是用于匹配字符串中字符组合的模式。在 JavaScript中，正则表达式也是对象。这些模式被用于 RegExp 的 exec 和 test 方法, 以及 String 的 match、replace、search 和 split 方法。本章介绍 JavaScript正则表达式。
创建一个正则表达式
1、使用一个正则表达式字面量，其由包含在斜杠之间的模式组成，如下所示：
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<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
/pattern/flags
*/
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/ab+c/<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/gi<span
class
=
"token punctuation"
>;</span></span></span></span></span></span></span></span></span></code>在加载脚本后，正则表达式字面值提供正则表达式的编译。当正则表达式保持不变时，使用此方法可获得更好的性能。<br><br>2、调用<code><a title=
"zh-CN/docs/JavaScript/Reference/Global Objects/RegExp"
href=
"https://developer.mozilla.org/zh-CN/docs/JavaScript/Reference/Global_Objects/RegExp"
>RegExp</a></code>对象的构造函数
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<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
new RegExp(pattern [, flags])
*/
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"ab+c"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"^[a-zA-Z]+[0-9]*\\W?_$"
<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;<br><br></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>
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正则表达式是用于匹配字符串中字符组合的模式。在 JavaScript中，正则表达式也是对象。这些模式被用于 RegExp 的 exec 和 test 方法, 以及 String 的 match、replace、search 和 split 方法。本章介绍 JavaScript正则表达式。
创建一个正则表达式
1、使用一个正则表达式字面量，其由包含在斜杠之间的模式组成，如下所示：
|
1
2
3
4
5
6
7
|
<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
/pattern/flags
*/
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/ab+c/<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/gi<span
class
=
"token punctuation"
>;</span></span></span></span></span></span></span></span></span></code>在加载脚本后，正则表达式字面值提供正则表达式的编译。当正则表达式保持不变时，使用此方法可获得更好的性能。<br><br>2、调用<code><a title=
"zh-CN/docs/JavaScript/Reference/Global Objects/RegExp"
href=
"https://developer.mozilla.org/zh-CN/docs/JavaScript/Reference/Global_Objects/RegExp"
>RegExp</a></code>对象的构造函数
|
|
1
2
3
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5
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7
8
9
|
<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
new RegExp(pattern [, flags])
*/
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"ab+c"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"^[a-zA-Z]+[0-9]*\\W?_$"
<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;<br><br></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>
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