javascript

Chapter 15: XML in JavaScript
If none of the XML parsers is available, then the function simply throws an error indicating that it could
not continue.
This function can be used to parse any XML string and should always be wrapped in a try - catch
statement just in case a parsing error occurs. Here’s an example:
var xmldom = null;
try {
xmldom = parseXml(“ < root > < child/ > < /root > ”);
} catch (ex){
alert(ex.message);
}
//further processing
For XML serialization, the same process can be followed to write a function that works in the four major
browsers. For example:
function serializeXml(xmldom){
if (typeof XMLSerializer != “undefined”){
return (new XMLSerializer()).serializeToString(xmldom);
} else if (document.implementation.hasFeature(“LS”, “3.0”)){
var implementation = document.implementation;
var serializer = implementation.createLSSerializer();
return serializer.writeToString(xmldom);
} else if (typeof xmldom.xml != “undefined”){
return xmldom.xml;
}
} else {
throw new Error(“Could not serialize XML DOM.”);
}
The serializeXml() function accepts a single argument, which is the XML DOM document to
serialize. As with the parseXml() function, the first step is to check for the most widely available
solution, which is XMLSerializer . If this type is available, then it is used to return the XML string for
the document. Otherwise, the DOM Level 3 solution is attempted with the final step being to use
ActiveX. Since the ActiveX approach simply uses the xml property, the function checks for that property
specifically. If each of these three attempts fails, then the method throws an error indicating that
serialization could not take place. Generally, serialization attempts shouldn ’ t fail if you ’ re using the
appropriate XML DOM object for the browser, so it shouldn ’ t be necessary to wrap a call to
serializeXml() in a try - catch . Instead, you can simply use this:
var xml = serializeXml(xmldom);
Note that due to differences in serializing logic, you may not end up with exactly the same serialization
results from browser to browser.
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