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How can I turn a string of HTML into a DOM object in a Firefox extension?

How can I turn a string of HTML into a DOM object in a Firefox extension?

"I'm downloading a web page (tag soup HTML) with XMLHttpRequest and I want to take the output and turn it into a DOM object that I can then run XPATH queries on. How do I convert from a string into DOM object?
It appears that the general solution is to create a hidden iframe and throw the contents of the string into that. There has been talk of updating DOMParser to support text/html but as of Firefox 3.0.1 you still get an NS_ERROR_NOT_IMPLEMENTED if you try.
Is there any option besides using the hidden iframe trick? And if not, what is the best way to do the iframe trick so that your code works outside the context of any currently open tabs (so that closing tabs won't screw up the code, etc)?
This is an example of why I'm looking for a solution other than the iframe hack, if I have to write all that code to have a robust solution, then I'd rather keep looking for something else."

Asked by: Guest | Views: 58
Total answers/comments: 4
Guest [Entry]

"Ajaxian actually had a post on inserting / retrieving html from an iframe today. You can probably use the js snippet they have posted there.

As for handling closing of a browser / tab, you can attach to the onbeforeunload (http://msdn.microsoft.com/en-us/library/ms536907(VS.85).aspx) event and do whatever you need to do."
Guest [Entry]

"Try this:

var request = new XMLHttpRequest();

request.overrideMimeType( 'text/xml' );
request.onreadystatechange = process;
request.open ( 'GET', url );
request.send( null );

function process() {
if ( request.readyState == 4 && request.status == 200 ) {
var xml = request.responseXML;

Notice the overrideMimeType and responseXML. The readyState == 4 is 'completed'."
Guest [Entry]

"Try creating a div

document.createElement( 'div' );

And then set the tag soup HTML to the innerHTML of the div. The browser should process that into XML, which then you can parse.

The innerHTML property takes a string
that specifies a valid combination of
text and elements. When the innerHTML
property is set, the given string
completely replaces the existing
content of the object. If the string
contains HTML tags, the string is
parsed and formatted as it is placed
into the document."
Guest [Entry]

So you want to download a webpage as an XML object using javascript, but you don't want to use a webpage? Since you have no control over what the user will do (closing tabs or windows or whatnot) you would need to do this in like a OSX Dashboard widget or some separate application. A Firefox extension would also work, unless you have to worry about the user closing the browser.