Add hooks.js for Ajax request intercepting

src/tracker/hooks.js

@@ -0,0 +1,31 @@
+var HOOKS = (function(){
+  return {
+    /*
+     * Intercepts an AJAX response, and passes the original request open() arguments and the request object itself to the provided function.
+     */
+    onAjaxResponse: function(func){
+      var prevOpen = XMLHttpRequest.prototype.open;
+      var prevSend = XMLHttpRequest.prototype.send;
+      
+      XMLHttpRequest.prototype.open = function(){
+        this.$requestArguments = arguments;
+        return prevOpen.apply(this, arguments);
+      };
+      
+      XMLHttpRequest.prototype.send = function(){
+        var req = this;
+        var prevEvent = this.onreadystatechange;
+        
+        this.onreadystatechange = function(){
+          if (req.readyState === XMLHttpRequest.DONE && req.status === 200){
+            func(this.$requestArguments, req);
+          }
+          
+          return prevEvent.apply(this, arguments);
+        };
+        
+        return prevSend.apply(this, arguments);
+      };
+    }
+  };
+})();