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Chapter 17. The Document Object Model > Convenience Methods: The Traversal and ...

17.5. Convenience Methods: The Traversal and Range APIs

So far in this chapter, we've discussed the core DOM API, which provides basic methods for document traversal and manipulation. The DOM standard also defines other optional API modules, the most important of which will be discussed in the chapters that follow. Two of the optional modules are essentially convenience APIs built on top of the core API. The Traversal API defines advanced techniques for traversing a document and filtering out nodes that are not of interest. The Range API defines methods for manipulating contiguous ranges of document content, even when that content does not begin or end at a node boundary. The Traversal and Range APIs are briefly introduced in the sections that follow. See the DOM reference section for complete documentation. The Range API is implemented by Netscape 6.1 (and partially implemented by Netscape 6), and the Traversal API is expected to be fully supported by Mozilla 1.0, which means that a future release of Netscape will support it. At the time of this writing, IE does not support either of these APIs.

17.5.1. The DOM Traversal API

At the beginning of this chapter, we saw techniques for traversing the document tree by recursively examining each node in turn. This is an important technique, but it is often overkill; we do not typically want to examine every node of a document. We instead might want to examine only the <img> elements in a document, or to traverse only the subtrees of <table> elements. The Traversal API provides advanced techniques for this kind of selective document traversal. As noted previously, the Traversal API is optional and, at the time of this writing, is not implemented in major sixth-generation browsers. You can test whether it is supported by a DOM-compliant browser with the following:


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