RegExp.lastParen ($+) - JavaScript 编辑

Non-standard

This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The non-standard lastParen property is a static and read-only property of regular expressions that contains the last parenthesized substring match, if any. RegExp.$+ is an alias for this property.

Description

The lastParen property is static, it is not a property of an individual regular expression object. Instead, you always use it as RegExp.lastParen or RegExp['$+'].

The value of the lastParen property is read-only and modified whenever a successful match is made.

You can not use the shorthand alias with the dot property accessor (RegExp.$+), because the parser expects an expression with "+" in that case and a SyntaxError is thrown. Use the bracket notation for property access.

Examples

Using lastParen and $+

var re = /(hi)/g;
re.test('hi there!');
RegExp.lastParen; // "hi"
RegExp['$+'];     // "hi"

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• RegExp.input ($_)
• RegExp.lastMatch ($&)
• RegExp.leftContext ($`)
• RegExp.rightContext ($')
• RegExp.$1-$9