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
| 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 2017 Draft (ECMA-262) The definition of 'RegExp.prototype.source' in that specification. |
Draft |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
| "(?:)" for empty regexps | ? | 38 (38) | ? | ? | (Yes) |
| Escaping | ? | 38 (38) | ? | ? | ? |
| Prototype accessor property | ? | 41 (41) | ? | ? | ? |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
| "(?:)" for empty regexps | ? | ? | 38.0 (38) | ? | ? | ? |
| Escaping | ? | ? | 38.0 (38) | ? | ? | ? |
| Prototype accessor property | ? | ? | 41.0 (41) | ? | ? | ? |