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 lastMatch property is a static and read-only property of regular expressions that contains the last matched characters.
RegExp.$& is an alias for this property.
lastMatch property is static, it is not a property of an individual regular expression object. Instead, you always use it as
The value of the
lastMatch property is read-only and modified whenever a successful match is made.
You can not use the shorthand alias with the dot property accessor (
RegExp.$&), because the parser expects an expression with "&" in that case and a
SyntaxError is thrown. Use the bracket notation for property access.
var re = /hi/g; re.test('hi there!'); RegExp.lastMatch; // "hi" RegExp['$&']; // "hi"
Non-standard. Not part of any current specification.