javascript

Chapter 11: DOM Levels 2 and 3
var supportsTraversals = document.implementation.hasFeature(“Traversal”, “2.0”);
var supportsNodeIterator = (typeof document.createNodeIterator == “function”);
var supportsTreeWalker = (typeof document.createTreeWalker == “function”);
As stated previously, DOM traversals are a depth - first traversal of the DOM structure that allows
movement in at least two directions (depending on the type being used). A traversal is rooted at a given
node, and it cannot go any further up the DOM tree than that root. Consider the following HTML page:
< html >
< head >
< title > Example < /title >
< /head >
< body >
< p > < b > Hello < /b > world! < /p >
< /body >
< /html >
This page evaluates to the DOM tree represented in Figure 11 - 4 .
Document
Element html
Element head
Element body
Element title
Element p
Text Example
Element b
Text world!
Figure 11-4
Text Hello
Any node can be the root of the traversals. Suppose, for example, that the < body > element is the
traversal root. The traversal can then visit the < p > element, the < b > element, and the two text nodes that
are descendants of < body > ; however, the traversal can never reach the < html > element, the < head >
element, or any other node that isn ’ t in the < body > element ’ s subtree. A traversal that has its root at
document , on the other hand, can access all of the nodes in document. Figure 11-5 depicts a depth - first
traversal of a DOM tree rooted at document.
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