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Loading XML

This line of code creates an XML DOM that represents the XML code

<root/>

. If you specify a names-

pace URL in the first argument, you can further define the document element:

var oXmlDom = document.implementation.createDocument(“http://www.wrox.com”,

“root”, null);

This line of code creates an XML DOM representing

<a0:root xmlns:a0=”http://www.wrox.com”

. Mozilla automatically creates a namespace named

to represent the URL you entered for the

namespace.

Loading XML

Unlike Microsoft’s XML DOM, Mozilla’s only supports one method for loading data:

load()

. The

load()

method in Mozilla works exactly the same as the

load()

method in Internet Explorer. All you

need is to specify the XML file to load and whether to load it synchronously or asynchronously (default).

To load the XML file synchronously, the code is essentially the same as in IE:

oXmlDom.async = false;

oXmlDom.load(“test.xml”);

If you want to load a file asynchronously, things are a little bit different.

Mozilla doesn’t support Microsoft’s

readyState

property on the XML DOM (indeed,

readyState

isn’t

part of the DOM Level 3 Load and Save specification upon which Mozilla’s implementation is based).

Instead, Mozilla’s XML DOM fires a

load

event when the file has been fully loaded, meaning that you

must use the

onload

event handler to determine when DOM is ready:

oXmlDom.onload = function () {

alert(“Done”);

};

oXmlDom.load(“test.xml”);

Unfortunately, Mozilla’s XML DOM doesn’t support the

loadXML()

method. To parse an XML string

into a DOM, you must use the

DOMParser

object:

var oParser = new DOMParser();

var oXmlDom = oParser.parseFromString(“<root/>”, “text/xml”);

This code creates an XML DOM that represents

<root/>

. The

DOMParser

object is created in the first line,

and the second line uses its only method,

parseFromString()

, to create the XML DOM. This method

accepts two arguments, the XML string to parse and the content type of the string. To parse XML code, the

content type can be

“text/xml”

“application/xml”

; any other content type is ignored (although it

is possible to parse XHTML code using the content type

“application/xhtml+xml”

Prior to version 1.4, Mozilla only supported asynchronous loading of external files.

In 1.4, Mozilla introduced the

async

property and the capability to load files

synchronously.

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XML in JavaScript

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