new file mode 100644
--- /dev/null
+++ b/util.js
@@ -0,0 +1,19 @@
+function nsResolver(prefix) {
+    return {
+        xrd: 'http://docs.oasis-open.org/ns/xri/xrd-1.0',
+        pubsub: 'http://jabber.org/protocol/pubsub',
+        avatar_metadata: 'urn:xmpp:avatar:metadata',
+        avatar_data: 'urn:xmpp:avatar:data',
+        nickname: 'http://jabber.org/protocol/nick',
+    }[prefix] || null;
+}
+
+function parseXPath(elem, xpath, result)
+{
+    if (result === undefined)
+        result = XPathResult.FIRST_ORDERED_NODE_TYPE;
+    const value = elem.getRootNode().evaluate(xpath, elem, nsResolver, result, null);
+    if (result == XPathResult.FIRST_ORDERED_NODE_TYPE)
+        return value.singleNodeValue;
+    return value;
+}