common Xpath solution across browser

//select single node

 1 function selectsingleNode(context, expression, namespaces) {
 2         var doc = (context.nodeType != 9 ? context.ownerDocument : context);
 3 
 4         if (typeof doc.evaluate != "undefined") {
 5             var nsresolver = null;
 6             if (namespaces instanceof Object) {
 7                 nsresolver = function (prefix) {
 8                     return namespaces[prefix];
 9                 };
10             }
11 
12             var result = doc.evaluate(expression, context, nsresolver, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
13             return (result !== null ? result.singleNodeValue : null);
14         } else if (typeof context.selectSingleNode != "undefined") {
15 
16             //create namespace string
17             if (namespaces instanceof Object) {
18                 var ns = "";
19                 for (var prefix in namespaces) {
20                     if (namespaces.hasOwnProperty(prefix)) {
21                         ns += 'xmlns:' + prefix + "='" + namespaces[prefix] + "'";
22                     }
23                 }
24                 doc.setProperty("SelectionNamespaces", ns);
25             }
26             return context.selectSingleNode(expression);
27         } else {
28         throw new Error("no xpath engine found");
29         }
30     }

//select nodes

 1 function selectNodes(context, expression, namespaces) {
 2         var doc = (context.nodeType != 9 ? context.ownerDocument : context);
 3 
 4         if (typeof doc.evaluate != "undefined") {
 5             var nsresolver = null;
 6             if (namespaces instanceof Object) {
 7                 nsresolver = function (prefix) {
 8                     return namespaces[prefix];
 9                 };
10             }
11 
12             var result = doc.evaluate(expression, context, nsresolver, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
13             var nodes = new Array();
14 
15             if (result != null) {
16                 for (var i = 0, len = result.snapshotLength; i < len; i++) {
17                     nodes.push(result.snapshotItem(i));
18                 }
19             }
20 
21             return nodes;
22         } else if (typeof context.selectNodes != "undefined") {
23 
24             //create namespace string
25             if (namespaces instanceof Object) {
26                 var ns = "";
27                 for (var prefix in namespaces) {
28                     if (namespaces.hasOwnProperty(prefix)) {
29                         ns += "xmlns:" + prefix + "='" + namespaces[prefix] + "'";
30                     }
31                 }
32                 doc.setProperty("SelectionNamespaces", ns);
33             }
34             var result = context.selectNodes(expression);
35             var nodes = new Array();
36 
37             for (var i = 0, len = result.length; i < len; i++) {
38                 nodes.push(result[i]);
39             }
40 
41             return nodes;
42         } else {
43         throw new Error("no xpath engine found");
44         }
45     }