regExp.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.

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

See also

• RegExp.prototype.flags