javascript

The Document Object Model
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 DOM Level 1
as it relates to HTML pages in the browser and its implementation in JavaScript. The browsers that
have mostly complete implementations of DOM Level 1 are Internet Explorer (IE) 6 and later
(IE 5.5 has several missing features), Firefox, Safari, Chrome, and Opera 7.5 and later.
Note that all DOM objects are represented by COM objects in IE. This means that
the objects don ’ t behave or function the same way as native JavaScript objects.
These differences are highlighted throughout the chapter.
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 information and/or markup in the document.
Each node type has different characteristics, data, and methods, and each may have relationships