DOM Level Test - document.implementation.hasFeature

JavaScript Tutorials - Herong's Tutorial Examples - Version 2.21, by Dr. Herong Yang

JavaScript Tutorials - Herong's Tutorial Examples

∟W3C's Document Object Model (DOM) Specifications

∟DOM Level Test - document.implementation.hasFeature

This section provides a tutorial example of using the document.implementation.hasFeature() method to test DOM levels supported in a particular Web browser.

In DOM Level 1, 2, and 3 specifications, there is one method that will level you to test what levels of DOM specifications are supported in a specific Web browser: document.implementation.hasFeature(feature, level). It returns true, if the specified feature and level is supported by the Web browser. Note that the level must be specified in the dot format like 1.0, 2.0, or 3.0.

I used this method in the tutorial example to test what levels of DOM are supported by Web browsers on my machine.

<html>
<!-- DOM_Level_Test.html
   Copyright (c) 2013 by Dr. Herong Yang, herongyang.com
-->
<head>
<title>DOM Level Test</title>
</head>
<body><pre>
<script type="text/javascript">
   document.writeln("\nDOM Level 0 Test:");
   document.writeln("   document.bgColor = "+document.bgColor);

   for (var i=1; i<4; i++) {
      document.writeln("\nDOM Level "+i+".0 Test:");
      document.writeln("   Core "+i+".0 = "
         + document.implementation.hasFeature("Core", i+".0"));
      document.writeln("   HTML "+i+".0 = "
         + document.implementation.hasFeature("HTML", i+".0"));
   }
</script>
</pre></body>
</html>

When I use this script to test Internet Explorer 6.0, the result shows that DOM Core Level 1 is not supported. But DOM HTML Level 1 is supported, very strange.

DOM Level 0 Test:
   document.bgColor = #ffffff

DOM Level 1.0 Test:
   Core 1.0 = false
   HTML 1.0 = true

DOM Level 2.0 Test:
   Core 2.0 = false
   HTML 2.0 = false

DOM Level 3.0 Test:
   Core 3.0 = false
   HTML 3.0 = false

When I use this script to test Mozilla Firefox 2.0, the result shows that DOM Core Level 1 and 2, and DOM HTML Level 2 are supported. But DOM HTML Level 1 is not supported.

DOM Level 0 Test:
   document.bgColor = #ffffff

DOM Level 1.0 Test:
   Core 1.0 = false
   HTML 1.0 = true

DOM Level 2.0 Test:
   Core 2.0 = true
   HTML 2.0 = true

DOM Level 3.0 Test:
   Core 3.0 = false
   HTML 3.0 = false

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

Defining Your Own Object Types