javascript

Chapter 15: XML in JavaScript
Using the IE transformNode() method ensures that you don ’ t need to use a thread - safe DOM
document for the transformation.
Note that due to different XSLT engines in browsers, the results you receive from a
transformation may vary slightly or greatly from browser to browser. You should
never depend on an absolute transformation result using XSLT in JavaScript.
Summary
There is a great deal of support for XML and related technologies in JavaScript. Unfortunately, because
of an early lack of specifications, there are several different implementations for common functionality.
DOM Level 2 provides an API for creating empty XML documents but not for parsing or serialization.
Because of this lack of functionality, browser vendors began creating their own approaches. IE took the
following approach:
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IE introduced XML support through ActiveX objects, the same objects that could be used to
build desktop applications.
The MSXML library ships with Windows and is accessible from JavaScript.
This library includes support for basic XML parsing and serialization as well as complementary
technologies such as XPath and XSLT.
Firefox, on the other hand, implemented two new types to deal with XML parsing and serialization as
follows :
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The DOMParser type is a simple object that parses an XML string into a DOM document.
The XMLSerializer type performs the opposite operation, serializing a DOM document into
an XML string.
Due to the simplicity and popularity of these objects, Opera, Chrome, and Safari duplicated the
functionality, and these types are de facto standards in web development.
DOM Level 3 introduced a specification for an XPath API that has been implemented by Firefox, Safari,
Chrome, and Opera. The API enables JavaScript to run any XPath query against a DOM document and
retrieve the result regardless of its data type. IE implemented its own XPath support in the form of two
methods: selectSingleNode() and selectNodes() . Although much more limited than the DOM
Level 3 API, these methods provide basic XPath functionality to locate a node or set of nodes in a DOM
document.
The last related technology is XSLT, which has no public specification defining an API for its usage.
Firefox created the XSLTProcessor type to handle transformations via JavaScript and was soon copied
by Safari, Chrome, and Opera. IE implemented its own solution, both with the simple
transformNode() method and through a more complicated template/processor approach.
XML is now well supported in IE, Firefox, Chrome, Safari, and Opera. Even though the implementations
vary wildly between IE and the other browsers, there ’ s enough commonality to create reasonable
cross - browser functionality.
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