introduce a utils helper for prototype inheritance

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/utils.js b/lib/utils.js
index 9b5cfcb9..7ed7c9ad 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -39,6 +39,14 @@ var utils = {
     return document.evaluate(xpath, document.documentElement, namespaceResolver, resultType, null);
   },
 
+  /** Sets up prototype inheritance */
+  extend: function(base, sub) {
+    function surrogateCtor() { }
+    surrogateCtor.prototype = base.prototype;
+    sub.prototype = new surrogateCtor();
+    sub.prototype.constructor = sub;
+  },
+
   /** Creates a single DOM element from :html */
   createElementFromHtml: function(html) {
     var tmp = document.createElement("div");