files/en-us/web/javascript/reference/global_objects/boolean/tostring/index.md

metadata

title: Boolean.prototype.toString()
short-title: toString()
slug: Web/JavaScript/Reference/Global_Objects/Boolean/toString
page-type: javascript-instance-method
browser-compat: javascript.builtins.Boolean.toString
sidebar: jsref

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

{{InteractiveExample("JavaScript Demo: Boolean.prototype.toString()")}}

const flag1 = new Boolean(true);

console.log(flag1.toString());
// Expected output: "true"

const flag2 = new Boolean(1);

console.log(flag2.toString());
// Expected output: "true"

Syntax

toString()

Parameters

None.

Return value

A string representing the specified boolean value.

Description

The {{jsxref("Boolean")}} object overrides the toString method of {{jsxref("Object")}}; it does not inherit {{jsxref("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 {{jsxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{jsxref("Object.prototype.toString()")}}