JavaScript: Boolean Object

Boolean is the value of the property key "Boolean" of the global object.

console.log( window["Boolean"] === Boolean ); // true

Boolean is a function.

〔►see JavaScript: Data Types〕

// type of Boolean
console.log ( typeof Boolean === "function" ); // true
console.log ( Object.prototype.toString.call (Boolean) === "[object Function]" ) // true

The parent of Boolean is Function.prototype. 〔►see JavaScript: Prototype and Inheritance〕

// parent of Boolean
console.log ( Object.getPrototypeOf ( Boolean ) === Function.prototype ); // true

The purpose of Boolean is:

1. Implicitly called by JavaScript to convert value to true or false. e.g. in a if statement.
2. Implicitly called by JavaScript to convert true or false to string, by first converting the value to boolean object, then use method toString.
3. Has the property key "prototype" that holds valueOf and toString methods.

〔►see JavaScript: true, false〕

Boolean Constructor

〔►see JavaScript: Boolean Constructor〕

Properties

• Boolean.prototype

〔►see JavaScript: Boolean.prototype〕

Reference

ECMAScript® 2016 Language Specification#sec-boolean-constructor