JavaScript Tutorials - Herong's Tutorial Examples - 2.33, by Herong Yang
The "Boolean" Object Type - Wrapping Boolean Values into Objects
This section provides a quick description and a tutorial example script on the 'Boolean' built-in object type, which is used to create 'Boolean' objects.
The "Boolean" object type is a special built-in object type to be used to create a "Boolean" object, which is different than a Boolean value of the Boolean primitive type. It has the following main features:
Here is a tutorial example script showing some of those features:
// Boolean_Object_Type.js // Copyright (c) 2013 HerongYang.com. All Rights Reserved. // Creating a new Boolean object var isBetter = new Boolean("JavaScript">"Java"); // Checking this object println("\nAbout this \"isBetter\":"); println(" Type = "+(typeof isBetter)); println(" Instance Of Object: "+(isBetter instanceof Object)); println(" Instance Of Boolean: "+(isBetter instanceof Boolean)); // Using Boolean's inherited methods var v = isBetter.valueOf(); var s = isBetter.toString(); println("\nExecution result:"); println(" typeof isBetter = "+(typeof isBetter)); println(" typeof isBetter.valueOf() = "+(typeof v)); println(" typeof isBetter.toString() = "+(typeof s)); println("\nConverting to Boolean objects on the fly:"); println(" \"...\".toString() = " +(("JavaScript">"Java").toString()));
If you run this script with "jrunscript", you will get:
About this "isBetter": Type = object Instance Of Object: true Instance Of Boolean: true Execution result: typeof isBetter = object typeof isBetter.valueOf() = boolean typeof isBetter.toString() = string Converting to Boolean objects on the fly: "...".toString() = true
Now we know how to create "Boolean" objects with the "Boolean()" constructor.
Table of Contents
ECMAScript Language Specification and JavaScript Dialects
Data Types, Variables and Expressions
Creating, Accessing, and Manipulating Arrays
Defining and Calling Functions
Web Browser Supporting JavaScript
Server-Side and Client-Side Web Scripting
Defining Your Own Object Types
Inheritance of Properties and Methods through the Prototype Object Chain
'jrunscript' - JavaScript Shell Command from JDK
Using Functions as "Function" Objects
►Introduction to Built-in Object Types
Overview of Built-in Object Types
The "Object" Object Type - The Root Object Type
The "Global" Object Type - The Invisible Global Container
Global Properties and Functions Defined in ECMAScript
Global Properties and Functions Provided by "jrunscript"
The "Function" Object Type - Functions Are Objects
The "Array" Object Type - Arrays Are Objects
The "JSON" Object Type - parse() and stringify()
The "String" Object Type - Not Equal to String Primitive Type
►The "Boolean" Object Type - Wrapping Boolean Values into Objects
The "Number" Object Type - Not Equal to Number Primitive Type
The "Date" Object Type - Managing Dates and Times
The "RegExp" Object Type - Regular Expression Patterns
The "Error" Object Type - Runtime Exceptions
The "Math" Object Type - The Math Container
W3C's Document Object Model (DOM) Specifications