W3cubDocs

/JavaScript

RegExp.prototype.source

The source property returns a String containing the source text of the regexp object, and it doesn't contain the two forward slashes on both sides and any flags.

Property attributes of RegExp.prototype.source
Writable no
Enumerable no
Configurable yes

Examples

Using source

var regex = /fooBar/ig;

console.log(regex.source); // "fooBar", doesn't contain /.../ and "ig".

Empty regular expressions and escaping

Starting with ECMAScript 5, the source property no longer returns an empty string for empty regular expressions. Instead, the string (?:) is returned. In addition, line terminators (such as "\n") are escaped now.

new RegExp().source; // "(?:)"

new RegExp('\n').source === '\n';  // true, prior to ES5
new RegExp('\n').source === '\\n'; // true, starting with ES5

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
source
1
12
1
4
5
1
1
18
4
10.1
1
1.0
1.0
0.10.0
empty_regex_string
6
12
38
No
15
5
≤37
18
38
14
4.2
1.0
1.0
0.10.0
escaping
73
12
38
10
60
6
73
73
38
52
6
11.0
1.0
12.0.0
prototype_accessor
48
12
41
4
35
1.3
48
48
41
35
1
5.0
1.0
6.0.0

See also

© 2005–2021 MDN 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/RegExp/source