Professional JavaScript for Web Developers, 4th Edition

14The Document Object Model

WHAT'S IN THIS CHAPTER?

• Understanding the DOM as a hierarchy of nodes
• Working with the various node types
• Coding the DOM around browser incompatibilities and gotchas
• Mutation Observers

WROX.COM DOWNLOADS FOR THIS CHAPTER

Please note that all the code examples for this chapter are available as a part of this chapter's code download on the book's website at www.wrox.com/go/projavascript4e on the Download Code tab.

The Document Object Model (DOM) is an application programming interface (API) for HTML and XML documents. The DOM represents a document as a hierarchical tree of nodes, allowing developers to add, remove, and modify individual parts of the page. Evolving out of early Dynamic HTML (DHTML) innovations from Netscape and Microsoft, the DOM is now a truly cross-platform, language-independent way of representing and manipulating pages for markup.

DOM Level 1 became a W3C recommendation in October 1998, providing interfaces for basic document structure and querying. This chapter focuses on the features and uses of the DOM as it relates to HTML pages in the browser and the DOM JavaScript API.

NOTE   Note that all DOM objects are represented by COM objects in Internet Explorer 8 and earlier. This means that the objects don't behave or function the same way as native JavaScript objects.

HIERARCHY OF NODES

Any HTML or XML document can be represented as a hierarchy of nodes using the DOM. There are several node types, each representing different ...