Fetching xml with GM_xmlhttpRequest

Question

I'm trying to retrieve a page with greasemonkey and then extract a link from it, inserting the link into the current page. I'm having some trouble with:

GM_xmlhttpRequest({
method: "GET",
url: "http://www.test.net/search.php?file=test",

onload: function(data) 
{
    if (!data.responseXML) 
    {
        data.responseXML = new DOMParser().parseFromString(data.responseText, "text/xml");
    }
    alert("!");
    var xmldata = data.response.xml;
    var tests = xmldata.getElementsByTagName('test');
    alert(tests[0].innerHTML);
}

});

The page is valid, and GM_xmlhttpRequest returned it correctly as a string when I tried previously, but I can't seem to figure out how to make it so I can use node operations on it.Thanks in advance.

Edit - a second, related question

How should I refer to the current page so that I could pass it a to function, just as I would pass my fetched page? Ex

function FindTests(currentpage)
{
    currentpage.getElementById('blah');
}

where initially I pass it document, but later I use the fetched page. Sorry if the wording is confusing.

Answer 1

if the requested page is a well-formatted xml, then you are in the correct way.
but you should change data.response.xml to data.responseXML

and i THINK you can't do this with a XMLDocument (result of the xml parser) because .getElementById works in HTMLDocument.
however, you could do the following to have a valid HTMLDocument:

if (/^Content-Type: text\/xml/m.test(data.responseHeaders)) {
    data.responseXML = new DOMParser().parseFromString(data.responseText, "text/xml");
}
else if (/^Content-Type: text\/html/m.test(data.responseHeaders)) {
    var dt = document.implementation.createDocumentType("html", "-//W3C//DTD HTML 4.01 Transitional//EN", "http://www.w3.org/TR/html4/loose.dtd");
    var doc = document.implementation.createDocument(null, null, dt);

    // I have to find a workaround because this technique makes the html*/head/body tags to disappear.  
    var html = document.createElement('html');
    html.innerHTML = data.responseText;
    doc.appendChild(html);

    data.responseXML = doc;
}

source: http://userscripts.org/scripts/review/56489