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• 句法
• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

exec() method executes a search for a match in a specified string. Returns a result array, or null .

JavaScript RegExp 对象是 stateful when they have the global or sticky flags set (e.g. /foo/g or /foo/y ). They store a lastIndex from the previous match. Using this internally, exec() can be used to iterate over multiple matches in a string of text (with capture groups), as opposed to getting just the matching strings with String.prototype.match() .

A newer function has been proposed to simplify matching multiple parts of a string (with capture groups): String.prototype.matchAll() .

If you are executing a match simply to find true or false ，使用 RegExp.prototype.test() method or String.prototype.search() 代替。

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

regexObj.exec(str)
					

参数

str

The string against which to match the regular expression.

返回值

If the match succeeds, the exec() method returns an array (with extra properties index and input ; see below) and updates the lastIndex property of the regular expression object. The returned array has the matched text as the first item, and then one item for each parenthetical capture group of the matched text.

If the match fails, the exec() method returns null , and sets lastIndex to 0 .

描述

Consider the following example:

// Match "quick brown" followed by "jumps", ignoring characters in between
// Remember "brown" and "jumps"
// Ignore case
let re = /quick\s(brown).+?(jumps)/ig;
let result = re.exec('The Quick Brown Fox Jumps Over The Lazy Dog');
					

The following table shows the results for this script:

Object	Property/Index	描述	范例
result	[0]	The full string of characters matched	"Quick Brown Fox Jumps"
	[1], ...[ n ]	The parenthesized substring matches, if any. The number of possible parenthesized substrings is unlimited.	result[1] === "Brown" result[2] === "Jumps"
	index	The 0-based index of the match in the string.	4
	input	The original string that was matched against.	"The Quick Brown Fox Jumps Over The Lazy Dog"
re	lastIndex	The index at which to start the next match. 若 g is absent, this will always be 0 .	25
	ignoreCase	Indicates if the i flag was used to ignore case.	true
	global	Indicates if the g flag was used for a global match.	true
	multiline	Indicates if the m flag was used to search across multiple lines.	false
	source	The text of the pattern.	"quick\s(brown).+?(jumps)"

范例

Finding successive matches

If your regular expression uses the " g " flag, you can use the exec() method multiple times to find successive matches in the same string. When you do so, the search starts at the substring of str specified by the regular expression's lastIndex property ( test() will also advance the lastIndex property).  Note that the lastIndex property will not be reset when searching a different string, it will start its search at its existing lastIndex .

For example, assume you have this script:

let myRe = /ab*/g;
let str = 'abbcdefabh';
let myArray;
while ((myArray = myRe.exec(str)) !== null) {
  let msg = 'Found ' + myArray[0] + '. ';
  msg += 'Next match starts at ' + myRe.lastIndex;
  console.log(msg);
}
						

This script displays the following text:

Found abb. Next match starts at 3
Found ab. Next match starts at 9
						

警告： Do not place the regular expression literal (or RegExp constructor) within the while condition!

It will create an infinite loop if there is a match, due to the lastIndex property being reset upon each iteration.

Also, be sure that the global flag (" g ") is set, or it will also cause an infinite loop.

使用 exec() with RegExp literals

You can also use exec() without creating a RegExp object explicitly:

let matches = /(hello \S+)/.exec('This is a hello world!');
console.log(matches[1]);
						

This will log a message containing 'hello world!' .

规范

规范
ECMAScript (ECMA-262) The definition of 'RegExp.exec' in that specification.

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
exec	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 5	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs Yes

图例

完整支持

完整支持

另请参阅

• 正则表达式 chapter in the JavaScript 指南
• RegExp

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. 标准内置对象
2. RegExp
3. 特性
   1. RegExp.$1-$9
   2. RegExp.input ($_)
   3. RegExp.lastMatch ($&)
   4. RegExp.lastParen ($+)
   5. RegExp.leftContext ($`)
   6. RegExp.prototype.dotAll
   7. RegExp.prototype.flags
   8. RegExp.prototype.global
   9. RegExp.prototype.ignoreCase
   10. RegExp.prototype.multiline
   11. RegExp.prototype.source
   12. RegExp.prototype.sticky
   13. RegExp.prototype.unicode
   14. RegExp.rightContext ($')
   15. RegExpInstance.lastIndex
   16. get RegExp[@@species]
4. 方法
   1. RegExp.prototype.compile()
   2. RegExp.prototype.exec()
   3. RegExp.prototype.test()
   4. RegExp.prototype.toSource()
   5. RegExp.prototype.toString()
   6. RegExp.prototype[@@matchAll]()
   7. RegExp.prototype[@@match]()
   8. RegExp.prototype[@@replace]()
   9. RegExp.prototype[@@search]()
   10. RegExp.prototype[@@split]()
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()