The Symbol.match
well-known symbol specifies the matching of a regular expression against a string. This function is called by the String.prototype.match()
method.
Property attributes of Symbol.match
| |
---|---|
Writable | no |
Enumerable | no |
Configurable | no |
This function is also used to identify if objects have the behavior of regular expressions. For example, the methods String.prototype.startsWith()
, String.prototype.endsWith()
and String.prototype.includes()
, check if their first argument is a regular expression and will throw a TypeError
if they are. Now, if the match
symbol is set to false
(or a Falsy value), it indicates that the object is not intended to be used as a regular expression object.
sRegExp
checkThe following code will throw a TypeError
:
'/bar/'.startsWith(/bar/); // Throws TypeError, as /bar/ is a regular expression // and Symbol.match is not modified.
However, if you set Symbol.match
to false
, the isRegExp
check (that uses the match
property) will indicate that the object is not a regular expression object. The methods startsWith
and endsWith
won't throw a TypeError
as a consequence.
var re = /foo/; re[Symbol.match] = false; '/foo/'.startsWith(re); // true '/baz/'.endsWith(re); // false
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Symbol.match' in that specification. | Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Symbol.match' in that specification. | Draft |
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 50 | 40 (40) | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 40.0 (40) | No support | No support | No support |
© 2005–2017 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/match