From 11f25aa99511de8e99c1534265de0cca3740379a Mon Sep 17 00:00:00 2001
From: Sam Stephenson <sam@37signals.com>
Date: Sat, 11 Aug 2007 19:53:39 +0000
Subject: [PATCH] prototype: Make sure Element#observe is always chainable.

---
 CHANGELOG            |  2 +-
 src/event.js         |  2 +-
 test/unit/event.html | 11 +++++++++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 2d0ef6b..12904e1 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,6 @@
 *SVN*
 
-* Make sure Element#stopObserving is always chainable.  [sam]
+* Make sure Element#observe and Element#stopObserving are always chainable.  [sam]
 
 * Event.fire/Element#fire now returns the newly-fired event instead of the event's target element.  [sam]
 
diff --git a/src/event.js b/src/event.js
index 6a6d68b..3cac071 100644
--- a/src/event.js
+++ b/src/event.js
@@ -170,7 +170,7 @@ Object.extend(Event, (function() {
       var id = getEventID(element), name = getDOMEventName(eventName);
       
       var wrapper = createWrapper(id, eventName, handler);
-      if (!wrapper) return false;
+      if (!wrapper) return element;
       
       if (element.addEventListener) {
         element.addEventListener(name, wrapper, false);
diff --git a/test/unit/event.html b/test/unit/event.html
index 6c2f365..df761a4 100644
--- a/test/unit/event.html
+++ b/test/unit/event.html
@@ -183,15 +183,22 @@
       assertEqual(0, Event.cache[eventID].somethingHappened.length);
     }},
     
-    testStopObservingIsChainable: function() { with(this) {
+    testObserveAndStopObservingAreChainable: function() { with(this) {
       var span = $("span"), observer = function() { };
-      span.observe("somethingHappened", observer);
+
+      assertEqual(span, span.observe("somethingHappened", observer));
       assertEqual(span, span.stopObserving("somethingHappened", observer));
+
       span.observe("somethingHappened", observer);
       assertEqual(span, span.stopObserving("somethingHappened"));
+
       span.observe("somethingHappened", observer);
       assertEqual(span, span.stopObserving());
       assertEqual(span, span.stopObserving()); // assert it again, after there are no observers
+
+      span.observe("somethingHappened", observer);
+      assertEqual(span, span.observe("somethingHappened", observer)); // try to reuse the same observer
+      span.stopObserving();
     }},
     
     testDocumentContentLoadedEventFiresBeforeWindowLoad: function() { with(this) {