jQuery / Ajax : How to filter XML data

Here is my code..

function getAnswer(answerUrl)
{
    $.ajax({
        type : 'GET',
        url  : answerUrl,
        async: false,   
        cache: false,
        dataType: 'xml',
        autoencode: true,
        success : function(data)
        {
            xml_answer = data;
            var xml_str = new XMLSerializer().serializeToString(xml_answer.documentElement);
            xml_answer= xml_str.replace(/<(/?)([^:>s]*:)?([^>]+)>/g, "<$1$3>");   
        }

So basically this returns every instance of the data. But I want to filter the data as to only get whatever contains "name=foo." Here is an example of the XML.

<TheoryNames xmlns:ns2="http://www.theory.com/namespace/xxx" xmlns:ns3="http://www.theory.org/LLC/des/xx" xmlns:ns4="http://www.theory.com/num/intelligence/work/llc/xx" name="foo" description="foo description" status="positive">
    <date>1.2.3</date>
</TheoryNames>

This is obviously repeated over and over in the XML file and the data differs.