Boolean.prototype.toString()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The toString() method of Boolean values returns a string representing the specified boolean value.

Try it

Syntax

toString()

Parameters

None.

Return value

A string representing the specified boolean value.

Description

The Boolean object overrides the toString method of Object; it does not inherit Object.prototype.toString(). For Boolean values, the toString method returns a string representation of the boolean value, which is either "true" or "false".

The toString() method requires its this value to be a Boolean primitive or wrapper object. It throws a TypeError for other this values without attempting to coerce them to boolean values.

Because Boolean doesn't have a [Symbol.toPrimitive]() method, JavaScript calls the toString() method automatically when a Boolean object is used in a context expecting a string, such as in a template literal. However, boolean primitive values do not consult the toString() method to be coerced to strings — rather, they are directly converted using the same algorithm as the initial toString() implementation.

Boolean.prototype.toString = () => "Overridden";
console.log(`${true}`); // "true"
console.log(`${new Boolean(true)}`); // "Overridden"

Examples

Using toString()

const flag = new Boolean(true);
console.log(flag.toString()); // "true"
console.log(false.toString()); // "false"

Specifications

Specification
ECMAScript Language Specification # sec-boolean.prototype.tostring

Browser compatibility

	Desktop					Mobile						Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	Deno	Node.js
`toString`	1	12	1	4	1	18	4	10.1	1	1.0	4.4	1.0	0.10.0