RegExp.prototype.source
BaselineWidely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Thesource accessor property ofRegExp instances returns a string containing the source text of this regular expression, without the two forward slashes on both sides or any flags.
Try it
const regex1 = /fooBar/gi;console.log(regex1.source);// Expected output: "fooBar"console.log(new RegExp().source);// Expected output: "(?:)"console.log(new RegExp("\n").source === "\\n");// Expected output: true (starting with ES5)// Due to escapingDescription
Conceptually, thesource property is the text between the two forward slashes in the regular expression literal. The language requires the returned string to be properly escaped, so that when thesource is concatenated with a forward slash on both ends, it would form a parsable regex literal. For example, fornew RegExp("/"), thesource is\\/, because if it generates/, the resulting literal becomes///, which is a line comment. Similarly, allline terminators will be escaped because line terminatorcharacters would break up the regex literal. There's no requirement for other characters, as long as the result is parsable. For empty regular expressions, the string(?:) is returned.
Examples
Using source
const regex = /fooBar/gi;console.log(regex.source); // "fooBar", doesn't contain /.../ and "gi".Empty regular expressions and escaping
new RegExp().source; // "(?:)"new RegExp("\n").source === "\\n"; // true, starting with ES5Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-get-regexp.prototype.source |