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MSXML

try {

var oXmlDom = new ActiveXObject(arrSignatures[i]);

return oXmlDom;

} catch (oError) {

//ignore

}

throw new Error(“MSXML is not installed on your system.”);

} else if (document.implementation && document.implementation.createDocument) {

var oXmlDom = document.implementation.createDocument(“”,””,null);

return oXmlDom;

} else {

throw new Error(“Your browser doesn’t support an XML DOM object.”);

}

The next task is to make Mozilla support the

readyState

property and the

onreadystatechange

event handler. This requires you to make some additional changes to the

Document

class.

First, add a

readyState

property and initialize it to 0.

Document.prototype.readyState = 0;

Next, create an

onreadystatechange

property and assign it the value of

null

Document.prototype.onreadystatechange = null;

Whenever the

readyState

property changes, the

onreadystatechange

function must be called. To

facilitate this, it’s best to create a method:

Document.prototype.__changeReadyState__ = function (iReadyState) {

this.readyState = iReadyState;

if (typeof this.onreadystatechange == “function”) {

this.onreadystatechange();

}

};

This method takes the new ready state as an argument and assigns it to the

readyState

property. Be

sure you check that

onreadystatechange

is actually a function before calling it (otherwise, this causes

an error). Because this method shouldn’t be called outside of the

Document

object, it uses the JavaScript

notation for a private method (leading and trailing double underscores).

Internet Explorer ’s XML DOM supports five ready states, but there is no way to mimic all of them for

Mozilla. Really, the only important value for

readyState

, which indicates that the XML DOM is

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XML in JavaScript

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