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Learn Javascript

Document Object Model

Introduction

The basic Document Object Model references allow access to very few of the basic components of a web page. A means of accessing more of the web page to allow for dynamic effects to be created was needed.

Before such a standard was developed for the Document Object Model, Microsoft introduced their own version so as to permit interaction with all of the objects on a web page using Javascript. This DOM is often known as the "all" DOM since objects within the Internet Explorer DOM are typically accessed using document.all.

This DOM is the only one supported by Internet Explorer 4. More recent versions of Internet Explorer and Opera also support this DOM as well as supporting the standard DOM. No one uses Internet Explorer 4 any more so there is no need to use this DOM any more since the standard DOM is also supported by most other browsers as well as Internet Explorer 5+.

Using What You Know

When you are looking at pre-written scripts to add to your site see if they contain any references to document.all. If you find such a reference outside of a function testing for which DOMs that the browser supports then throw the script away as it is not written to support modern web browsers.

Past Lessons

  1. Introduction
  2. Decision Making
  3. Functions
  4. Maintain and Test
  5. External Script and Noscript
  6. Object Oriented Javascript
  7. Loops
  8. More Predefined Classes

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