Javascript Xpath and default namespaces

Question

Javascript Xpath and default namespaces

I have JavaScript / Xpath not working as I expected. ( available at jsfiddle ) It seems that I am doing something wrong with the XML namespace, preventing me from querying my elements by their node (tags).

If I try to query for all child nodes of the current node, I find the element myElement

with no problem:

    var xpathResult = xmlDoc.evaluate( "child::*", rootElement, nsResolver, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    var queryEl;
    if(queryEl = xpathResult.iterateNext()) {
        alert("child::* found element " + queryEl.nodeName);
    }
    else {
        alert("child::* found nothing!");
    }

... but if I specifically target nodes named myElement

node (tag) I don't get any results:

    /* Now try getting only those children with nodeName `myElement` */
   xpathResult = xmlDoc.evaluate( "child::myElement", rootElement, nsResolver, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    var queryEl;
    if(queryEl = xpathResult.iterateNext()) {
        alert("child::myElement found element " + queryEl.nodeName);
    }
    else {
        alert("child::myElement found nothing!");
    }

What am I doing wrong?

+3

javascript xpath xml-namespaces

Richard JP Le Guen 08 Mar 12 at 17:02

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1 answer

Yoshi · Accepted Answer · 2012-03-08T17:38:30+0000

Try this as your resolver:

var nsResolver = (function (element) {
    var
      nsResolver = element.ownerDocument.createNSResolver(element),
      defaultNamespace = element.getAttribute('xmlns');

    return function (prefix) {
       return nsResolver.lookupNamespaceURI(prefix) || defaultNamespace;
    };
} (xmlDoc.documentElement));

You will also need to select items like this:

"child::default:myElement"
// where 'default' can be anything, as long as there is a namespace

Javascript Xpath and default namespaces

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