Ensure the target property on events is never undefined in IE. [#383 state:resolved]

CHANGELOG

@@ -1,3 +1,5 @@
+* Ensure the `target` property on events is never undefined in IE. [#383 state:resolved] (Mathias Karstädt, Diego Perini, Andrew Dupont)
+
 * Ensure Element#descendants always returns an array. [#373 state:resolved] (kangax)
 
 * Don't switch fixed position elements to absolute in Element.getDimensions [#543 state:resolved] (James Wheare)

src/dom/event.js

@@ -142,18 +142,22 @@
     });
 
     // IE's method for extending events.
-    Event.extend = function(event) {
+    Event.extend = function(event, element) {
       if (!event) return false;
       if (event._extendedByPrototype) return event;
 
       event._extendedByPrototype = Prototype.emptyFunction;
       var pointer = Event.pointer(event);
+      
+      // The optional `element` argument gives us a fallback value for the
+      // `target` property in case IE doesn't give us through `srcElement`.
       Object.extend(event, {
-        target: event.srcElement,
+        target: event.srcElement || element,
         relatedTarget: _relatedTarget(event),
         pageX:  pointer.x,
         pageY:  pointer.y
       });
+      
       return Object.extend(event, methods);
     };
   } else {
@@ -171,7 +175,7 @@
       // First time we've handled this element. Put it into the cache.
       CACHE.push(element);
       registry = Element.retrieve(element, 'prototype_event_registry', $H());    
-    }    
+    }
 
     var respondersForEvent = registry.get(eventName);
     if (Object.isUndefined()) {
@@ -195,13 +199,13 @@
         if (event.eventName !== eventName)
           return false;
           
-        Event.extend(event);
+        Event.extend(event, element);
         handler.call(element, event);
       };
     } else {
       // Ordinary event.
       responder = function(event) {
-        Event.extend(event);
+        Event.extend(event, element);
         handler.call(element, event);
       };
     }

test/functional/event.html

@@ -229,10 +229,15 @@
   
   <script type="text/javascript">
     $('addunload').observe('click', function(e){
-      if (this._done) return
+      if (this._done) return;
 
       window.onunload = function(){ alert('inline unload fired!') }
-      Event.observe(window, 'unload', function(){ alert('observed unload fired!') })
+      Event.observe(window, 'unload', function(event){
+        if (!event.target) {
+          alert('FAILURE: event.target should not be null!');
+        }
+        alert('observed unload fired!')
+      });
 
       this.update('Registered two unload events, one inline ("onunload") and one regular - try to refresh, both should fire')
       this._done = true