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.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
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
Specification | Status | Comment |
---|---|---|
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.2. JavaScript 1.5: source is a property of a RegExp instance, not the RegExp object. |
ECMAScript 5.1 (ECMA-262) The definition of 'RegExp.prototype.source' in that specification. |
Standard | The source property for empty regular expressions now returns "(?:)" instead of an empty string. A definition for the escaping behavior has been added. |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'RegExp.prototype.source' in that specification. |
Standard | source is now a prototype accessor property rather than an instance's own data property. |
ECMAScript Latest Draft (ECMA-262) The definition of 'RegExp.prototype.source' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | Yes | Yes | 1 | Yes | Yes | Yes |
Prototype accessor property (ES2015) | Yes | ? | 41 | ? | Yes | Yes |
Escaping | ? | ? | 38 | ? | ? | ? |
"(?:)" for empty regexps | Yes | ? | 38 | ? | ? | Yes |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
---|---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | 4 | Yes | Yes | Yes |
Prototype accessor property (ES2015) | Yes | Yes | ? | 41 | Yes | Yes | Yes |
Escaping | ? | ? | ? | 38 | ? | ? | ? |
"(?:)" for empty regexps | ? | ? | ? | 38 | ? | ? | ? |