RegExp.input ($_)

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 input property is a static property of regular expressions that contains the string against which a regular expression is matched. RegExp.$_ is an alias for this property.




The input property is static, it is not a property of an individual regular expression object. Instead, you always use it as RegExp.input or RegExp.$_.

The value of the input property is modified whenever the searched string on the regular expression is changed and that string is matching.


Using input and $_

var re = /hi/g;
re.test("hi there!");
RegExp.input;         // "hi there!"
re.test("foo");       // new test, non-matching
RegExp.$_;            // "hi there!"
re.test("hi world!"); // new test, matching
RegExp.$_;            // "hi world!"


Non-standard. Not part of any current specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

 Contributors to this page: fscholz
 Last updated by: fscholz,