From 9d7a981e4c434ee7ca5a1219ab5a150552c411d1 Mon Sep 17 00:00:00 2001
From: Andrew Dupont <prototype@andrewdupont.net>
Date: Sat, 28 Feb 2009 10:07:08 -0600
Subject: [PATCH] Add first-class support for `mouseenter` and `mouseleave`
 events in non-IE browsers (IE supports them natively). [#350 state:resolved]
 (Nick Stakenburg, Andrew Dupont)

---
 CHANGELOG                  |  2 ++
 src/dom/event.js           | 55 +++++++++++++++++++++++++++++++-------
 test/functional/event.html | 19 +++++++++++++
 3 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index b2bfd82..8ae576b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Add first-class support for `mouseenter` and `mouseleave` events in non-IE browsers (IE supports them natively). [#350 state:resolved] (Nick Stakenburg, Andrew Dupont)
+
 * Make sure `_extendedByPrototype`, `_countedByPrototype`, and `prototypeUID` node expandos are accessed with `typeof` to prevent errors in some environments. [#354 state:resolved] (Hilberty, kangax, Andrew Dupont)
 
 * Fix issue where Opera 9.x returns incorrect results on certain Selector queries with descendant combinators. [#395 state:resolved] (Arpan, fearphage, kangax, Andrew Dupont)
diff --git a/src/dom/event.js b/src/dom/event.js
index 0fa3fec..89b6bf1 100644
--- a/src/dom/event.js
+++ b/src/dom/event.js
@@ -286,11 +286,33 @@
         handler.call(element, event);
       };
     } else {
-      // Ordinary event.
-      responder = function(event) {
-        Event.extend(event, element);
-        handler.call(element, event);
-      };
+      // Non-custom event.
+      if (!Prototype.Browser.IE &&
+       (eventName === "mouseenter" || eventName === "mouseleave")) {
+        // If we're dealing with mouseenter or mouseleave in a non-IE browser,
+        // we create a custom responder that mimics their behavior within
+        // mouseover and mouseout.
+        if (eventName === "mouseenter" || eventName === "mouseleave") {
+          responder = function(event) {
+            Event.extend(event, element);
+            
+            var parent = event.relatedTarget;
+            while (parent && parent !== element) {
+              try { parent = parent.parentNode; }
+              catch(e) { parent = element; }
+            }
+            
+            if (parent === element) return;
+            
+            handler.call(element, event);
+          };
+        }
+      } else {  
+        responder = function(event) {
+          Event.extend(event, element);
+          handler.call(element, event);
+        };
+      }
     }
 
     responder.handler = handler;
@@ -317,7 +339,16 @@
   // object when page is returned to via the back button using its bfcache.
   if (Prototype.Browser.WebKit)
     window.addEventListener('unload', Prototype.emptyFunction, false);
-
+    
+    
+  var _getDOMEventName = Prototype.K;
+  
+  if (!Prototype.Browser.IE) {
+    _getDOMEventName = function(eventName) {
+      var translations = { mouseenter: "mouseover", mouseleave: "mouseout" };      
+      return eventName in translations ? translations[eventName] : eventName;      
+    };
+  }
 
   /**
    *  Event.observe(element, eventName, handler) -> Element
@@ -342,11 +373,13 @@
         element.attachEvent("onfilterchange", responder);    
       }          
     } else {
+      var actualEventName = _getDOMEventName(eventName);
+      
       // Ordinary event.
       if (element.addEventListener)
-        element.addEventListener(eventName, responder, false);
+        element.addEventListener(actualEventName, responder, false);
       else
-        element.attachEvent("on" + eventName, responder);
+        element.attachEvent("on" + actualEventName, responder);
     }
 
     return element;
@@ -396,6 +429,8 @@
     var responder = responders.find( function(r) { return r.handler === handler; });
     if (!responder) return element;
     
+    var actualEventName = _getDOMEventName(eventName);
+    
     if (eventName.include(':')) {
       // Custom event.
       if (element.removeEventListener)
@@ -407,9 +442,9 @@
     } else {
       // Ordinary event.
       if (element.removeEventListener)
-        element.removeEventListener(eventName, responder, false);
+        element.removeEventListener(actualEventName, responder, false);
       else
-        element.detachEvent('on' + eventName, responder);
+        element.detachEvent('on' + actualEventName, responder);
     }
       
     registry.set(eventName, responders.without(responder));
diff --git a/test/functional/event.html b/test/functional/event.html
index 611d5e6..77c2a32 100644
--- a/test/functional/event.html
+++ b/test/functional/event.html
@@ -225,6 +225,25 @@
     })
   </script>
   
+  <p id="mouseenter"><code>mouseenter</code> test</p>
+  
+  <script type="text/javascript">
+    $('mouseenter').observe('click', function() {
+      $('mouseenter').insert("<br />carefully mouse over the word 'mouseenter', then outside of the box entirely");
+      $('mouseenter').observe('mouseenter', function(event) {
+        this.failed();
+        $('mouseenter').stopObserving();
+      });
+      $('mouseenter').observe('mouseleave', function(event) {
+        if ($(event.relatedTarget).descendantOf($('mouseenter'))) {
+          $('mouseenter').failed();
+        } else $('mouseenter').passed();
+        
+        $('mouseenter').stopObserving();
+      });
+    });
+  </script>
+  
   <p id="addunload">Add unload events</p>
   
   <script type="text/javascript">