Object Literals of the "Object" Type

This section provides a quick description of object literals or initializers for creating new objects of the 'Object' type. A tutorial example is provided on how to initialize an object with two properties and two methods.

In previous sections we learned that objects of "Object" type can be created with the constructor function "new Object()".

JavaScript also support a simpler way to create objects of "Object" type using object literals in the format of:

{property1: value1, property2: value2, ...}

where "property1" and "property2" are property or method names. In JavaScript language, properties and methods in an object are really managed in an identical way.

An object literal is also called object initializer, because it allows you to create a new object and to initialize it with properties and methods in a single operation.

Using an object literal to create an object has the same result as using the constructor. But object literals are much easier to use. The following two code segments are identical. But the first one is much simpler:

   // Creating an object with an object literal
   var obj = {property1: value1, property2: value2, ...};
  
   // Creating an object with the constructor
   var obj = new Object();
   obj.property1 = value1;
   obj.property2 = value2;
   ...;

Here is a tutorial example of creating an object of the "Object" type with an object literal, or initializer:

<html>
<!-- Object_Literal.html
   Copyright (c) 2013 by Dr. Herong Yang, herongyang.com
-->
<head>
<title>Object Literals of "Object" Type</title>
</head>
<body>
<pre>
<script type="text/javascript">

// Using "this" to get the properties
function myToString() {
   return '"'+this.title + '" by '+this.author;
}

// Using "this" to get the "toString" method
function showAll() {
   window.alert(this.toString());
}

   // Using object literal format
   var myBook = {
      author: "Herong Yang",
      title: "JavaScript Tutorials",
      print: showAll,
      toString: myToString
   };

   // Calling the method on "myBook"
   myBook.print();
</script>
</pre>
</body>
</html>

If you run this tutorial example, you will get the same result as the example in the previous section: "JavaScript Tutorials" by Herong Yang.

Table of Contents

 About This Book

 Introduction to JavaScript

 ECMAScript Language Specification and JavaScript Dialects

 Data Types, Variables and Expressions

 Flow Control Statements

 Creating, Accessing, and Manipulating Arrays

 Defining and Calling Functions

 Web Browser Supporting JavaScript

 Server-Side and Client-Side Web Scripting

Introduction to Objects

 What Is an Object?

 Objects of "Object" Data Type

 Adding and Deleting Object Own Properties

 Adding and Deleting Object Own Methods

 Using "this" Keyword to Represent Current Object

Object Literals of the "Object" Type

 Objects and Associate Arrays

 Objects with Indexed Properties

 Differences between "Object" and "Array"

 Using "Array" Objects as "Object" Objects

 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

 W3C's Document Object Model (DOM) Specifications

 References

 PDF Printing Version