XML DOM hacking in MSIE: halp!

[prog]

Righto, I just sacrificed a couple of hours on the altar of trying to get shit to work in MSIE. On the plus side, I think I can eliminate one of the third-party libraries I've been using; MSIE was barking at it, and I find that I can do the same thing it was doing using Prototype, which the application already depends on.

On the minus side, MSIE's XML API eludes me. Consider this code snippet. Given xml_request, an XMLHttpRequest object:

    alert(xml_request.responseText); // This prints the correct thing.
    var xml_doc = xml_request.responseXML;
    var root_element = xml_doc.documentElement;
    if (root_element) {
        alert("I have a document element. I am a sane browser!");
    }
    else {
        alert("I have no document element. I must be MSIE. Fuck.");
    }

The initial alert() makes me sure that MSIE (as well as any other browser) is in fact reading the XML. I just can't do a damn thing with it after that; every attempt to peek into any DOMmish properties of xml_doc returns null.

xml_doc.firstChild and equivalent statements all fail equally (while succeeding on sane browsers). Wha?

---

Another good reason to drop the library I am dropping? It contains lines of code like this:

MWJ_ldD[MWJ_ldD.length-1].onreadystatechange = new Function( 'if( MWJ_ldD['+(MWJ_ldD.length-1)+'].readyState == 4 ) { '+oFunct+'(MWJ_ldD['+(MWJ_ldD.length-1)+'].load?MWJ_ldD['+(MWJ_ldD.length-1)+']:MWJ_ldD['+(MWJ_ldD.length-1)+'].responseXML); }' );

Holy hannah. That's no way to make friends.

Comments

[chocorisu.livejournal.com]

msdn.microsoft.com... it's a pain to search but it's all on there. Handy trick: use "site:msdn.microsoft.com" to search it with Google. It'll be way less painful than using Microsoft's search tools.

[jaq.livejournal.com]

You might find Sarissa helpful?

[cnoocy]

Is xml_doc even defined? You may need different syntax there.

[ahkond.livejournal.com]

What do you get from alert(xml_request.responseXML)? Just to see whether it's empty or not ...

Is it possible that calling xml_request.responseText empties the xml_request object, and that subsequently calling .responseXML therefore returns an empty XML document?

[misuba.livejournal.com]

I'm betting that that library code is the result of a packing algorithm meant to reduce the time it takes to move the JS over the wire. There may be a more readable version available. OTOH, that looks pretty lengthy for packed JS.

I found a few articles on JS and XML that have techniques that might be helpful, but they aren't anything the most casual googler couldn't dig up. There is this, though, if you don't have something like it (it ain't Firebug but it's pretty handy): JavaScript Shell for IE

[misuba.livejournal.com]

OK, few more things:

Does xml_doc.nodeType evaluate to 9? It should.

Does going straight to xml_doc.childNodes yield anything fruitful?

Surprisingly, a look at the Prototype API docs doesn't reveal any special sauce for the responseXML property. You'd think that they had a basic browser incompatibility like this one handled.

[daerr.livejournal.com]

And xml_doc.documentElement.firstChild doesn't work?

I'm pretty sure that xml_doc.firstChild isn't actually valid.