Differences between "Object" and "Array"

This section provides a quick description of similarities and differences of 'Array' and 'Object'. A tutorial example is provided on how to compare an 'Array' object to an 'Object' object.

JavaScript supports a number of predefined core object types. Among them, "Object" and "Array" have very close relations. If you compare "Array" with "Object", you should see the following similarities and differences:

Here is a JavaScript tutorial example that shows how "Array" and "Object" are similar to each other:

<html>
<!-- Object_and_Array.html
   Copyright (c) 2013 by Dr. Herong Yang, herongyang.com
-->
<head>
<title>Comparing Object and Array</title>
</head>
<body>
<pre>
<script type="text/javascript">

   // Creating an object of "Array" - array literal
   var bookArray = [
      "JavaScript Tutorial", 
      "Herong Yang", 
      2008, 
      "Programming"
   ];

   // Creating an object of "Object" - object literal
   var bookObject = {
      title: "JavaScript Tutorial", 
      author: "Herong Yang", 
      year: 2008, 
      category: "Programming"
   };

   // Checking "bookArray"
   document.writeln();
   document.writeln("About the \"Array\" object:");
   document.writeln("   Type: "+(typeof bookArray));
   document.writeln("   Instance Of Object: "
      +(bookArray instanceof Object));
   document.writeln("   Instance Of Array: "
      +(bookArray instanceof Array));
   document.writeln("   Members:");
   for (var item in bookArray) {
      document.writeln("      "+item+": "+bookArray[item]);
   }

   // Checking "bookObject"
   document.writeln();
   document.writeln("About the \"Object\" object:");
   document.writeln("   Type: "+(typeof bookObject));
   document.writeln("   Instance Of Object: "
      +(bookObject instanceof Object));
   document.writeln("   Instance Of Array: "
      +(bookObject instanceof Array));
   document.writeln("   Members:");
   for (var item in bookObject) {
      document.writeln("      "+item+": "+bookObject[item]);
   }
</script>
</pre>
</body>
</html>

The output of this tutorial example shows that how an "Array" object is similar to an "Object" object:

About the "Array" object:
   Type: object
   Instance Of Object: true
   Instance Of Array: true
   Members:
      0: JavaScript Tutorial
      1: Herong Yang
      2: 2008
      3: Programming

About the "Object" object:
   Type: object
   Instance Of Object: true
   Instance Of Array: false
   Members:
      title: JavaScript Tutorial
      author: Herong Yang
      year: 2008
      category: Programming

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