match

Table of contents

  1. 1. Summary
  2. 2. Syntax
  3. 3. Parameters
  4. 4. Description
    1. 4.1. Notes
  5. 5. Examples
    1. 5.1. Example: Using match
    2. 5.2. Example: Using global and ignore case flags with match
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Summary

Used to retrieve the matches when matching a string against a regular expression.

Method of String
Implemented in JavaScript 1.2
ECMAScript Edition ECMAScript 3rd Edition

Syntax

string.match(regexp)

Parameters

Description

If the regular expression does not include the g flag, returns the same result as regexp.exec(string).

If the regular expression includes the g flag, the method returns an Array containing all matches. If there were no matches, the method returns null.

The returned Array has an extra input property, which contains the regexp that generated it as a result. In addition, it has an index property, which represents the zero-based index of the match in the string.

regexp
A regular expression object. If a non-RegExp object obj is passed, it is implicitly converted to a RegExp by using new RegExp(obj).

Gecko 8.0 note
(Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5)

Prior to Gecko 8.0 (Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5) , match() was implemented incorrectly; when it was called with no parameters or with undefined, it would match against undefined, instead of always returning an empty string. This is fixed.

Notes

  • If you need to know if a string matches a regular expression regexp, use regexp.test(string).
  • If you only want the first match found, you might want to use regexp.exec(string) instead.
  • See §15.5.4.10 of the ECMA-262 specification.

Examples

Example: Using match

In the following example, match is used to find "Chapter" followed by 1 or more numeric characters followed by a decimal point and numeric character 0 or more times. The regular expression includes the i flag so that case will be ignored.

<script type="text/javascript">
str = "For more information, see Chapter 3.4.5.1";
re = /(chapter \d+(\.\d)*)/i;
found = str.match(re);
alert(found);
</script>

This returns the array containing Chapter 3.4.5.1,Chapter 3.4.5.1,.1

"Chapter 3.4.5.1" is the first match and the first value remembered from (Chapter \d+(\.\d)*).

".1" is the second value remembered from (\.\d).

Example: Using global and ignore case flags with match

The following example demonstrates the use of the global and ignore case flags with match. All letters A through E and a through e are returned, each its own element in the array

var str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
var regexp = /[A-E]/gi;
var matches_array = str.match(regexp);
alert(matches_array);

matches_array now equals ['A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e']

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