December 20, 2000 - The Document's Virtual Root Node

Yehuda Shiran December 20, 2000
The Document's Virtual Root Node
Tips: December 2000

Yehuda Shiran, Ph.D.
Doc JavaScript

You can use the DOM (Document Object Model) to model the whole document. At the root of document model is the document object. But this node is only virtual: you cannot prompt its type, name, or ID. You can access these properties through the documentElement object attribute. If you would query the name of document.documentElement:

document.documentElement.nodeName

you would get HTML. Try it. You may also query the root's type:

document.documentElement.nodeType

You should get 1. Try it. There are three types:

HTML, BODY, HEAD)
  • 2 = Attribute (Examples:
    • ID, NAME, BGCOLOR)
  • 3 = Text (Free text between opening and closing tags. Example: text between
    • <P> and </P>)

    The node document.documentElement is the root of the document model. If you would query its first child:

    document.documentElement.firstChild.nodeName

    you would get the HEAD tag. Try it.

    The code in this tip can be viewed by all DOM-supporting browsers such as IE 5+ and Netscape 6.

    Learn more about the DOM in Columns 40, The DOM, Part I: Analysis, through Column 47, A DOM-Based Snakes Game, Part II.