JS: Boolean Object

By Xah Lee. Date: . Last updated: .

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

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

Boolean is a function.

〔►see JS: 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 JS: 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 JS: true, false

Boolean Constructor

〔►see JS: Boolean Constructor


〔►see JS: Boolean.prototype


ECMAScript® 2016 Language Specification#sec-boolean-constructor

Boolean Topic

  1. JS: true, false
  2. JS: Boolean Object
  3. JS: Boolean.prototype

Object and Inheritance Topic

  1. JS: Object System Overview
  2. JS: What's Object?
  3. JS: Prototype and Inheritance
  4. JS: Create Object
  5. JS: Object Literal Expression
  6. JS: Find Object's Prototype
  7. JS: How to Create Object with Parent X?
  8. JS: Prevent Adding Property
  9. JS: Determine Type of Object
  10. JS: Primitive Value Object Wrapper
  11. JS: Clone, Deep Copy Object/Array
  12. JS: Test Equality of Objects

  1. JS: Object Object
  2. JS: Object.prototype
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