RegExp.prototype.toString()

{{JSRef}}

The toString() method of {{jsxref("RegExp")}} instances returns a string representing this regular expression.

{{InteractiveExample("JavaScript Demo: RegExp.prototype.toString()", "taller")}}

console.log(new RegExp("a+b+c"));
// Expected output: /a+b+c/

console.log(new RegExp("a+b+c").toString());
// Expected output: "/a+b+c/"

console.log(new RegExp("bar", "g").toString());
// Expected output: "/bar/g"

console.log(new RegExp("\n", "g").toString());
// Expected output (if your browser supports escaping): "/\n/g"

console.log(new RegExp("\\n", "g").toString());
// Expected output: "/\n/g"

Syntax

toString()

Parameters

None.

Return value

A string representing the given object.

Description

The {{jsxref("RegExp")}} object overrides the toString() method of the {{jsxref("Object")}} object; it does not inherit {{jsxref("Object.prototype.toString()")}} . For {{jsxref("RegExp")}} objects, the toString() method returns a string representation of the regular expression.

In practice, it reads the regex’s source and flags properties and returns a string in the form /source/flags. The toString() return value is guaranteed to be a parsable regex literal, although it may not be the exact same text as what was originally specified for the regex (for example, the flags may be reordered).

Examples

Using toString()

The following example displays the string value of a {{jsxref("RegExp")}} object:

const myExp = new RegExp("a+b+c");
console.log(myExp.toString()); // '/a+b+c/'

const foo = new RegExp("bar", "g");
console.log(foo.toString()); // '/bar/g'

Empty regular expressions and escaping

Since toString() accesses the source property, an empty regular expression returns the string "/(?:)/", and line terminators such as \n are escaped. This makes the returned value always a valid regex literal.

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

new RegExp("\n").toString() === "/\\n/"; // true

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

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