add an undelegate method to View and pass back the listener from delegate

backbone.js

@@ -1129,17 +1129,19 @@
 
     // Add a single event listener to the element responding only to the
     // optional `selector` or catches all `eventName` events. Subclasses can
-    // override this to utilize an alternative DOM event management API.
+    // override this to utilize an alternative DOM event management API. Returns
+    // the listener for easy undelegation with `undelegate`.
     delegate: function(eventName, selector, listener) {
       eventName += '.delegateEvents' + this.cid;
-      if (!selector) {
+      // When `delegate` is called with two arguments, `selector` is actually
+      // the `listener`
+      var listener = _.isFunction(selector) ? selector : listener;
+      if (selector === '') {
         this.$el.on(eventName, listener);
       } else {
-        // When `delegate` is called with two arguments, `selector` is actually
-        // the `listener`
         this.$el.on(eventName, selector, listener);
       }
-      return this;
+      return listener;
     },
 
     // Clears all callbacks previously bound to the view by `delegateEvents`.
@@ -1150,6 +1152,13 @@
       return this;
     },
 
+    // Remove a single event from the delegated events. `selector` and `listener`
+    // are both optional.
+    undelegate: function(eventName, selector, listener) {
+      eventName += '.delegateEvents' + this.cid;
+      this.$el.off(eventName, selector, listener);
+    },
+
     // Ensure that the View has a DOM element to render into.
     // If `this.el` is a string, pass it through `$()`, take the first
     // matching element, and re-assign it to `el`. Otherwise, create

test/view.js

@@ -144,6 +144,37 @@
     equal(counter2, 3);
   });
 
+  test("undelegate", 0, function() {
+    view.delegate('click', function() { ok(false); });
+    view.delegate('click', 'h1', function() { ok(false); });
+
+    view.undelegate('click');
+
+    view.$('h1').trigger('click');
+    view.$el.trigger('click');
+  })
+
+  test("undelegate with passed handler", 1, function() {
+    var listener = view.delegate('click', function() { ok(false); });
+    view.delegate('click', function() { ok(true); });
+    view.undelegate('click', listener);
+    view.$el.trigger('click');
+  });
+
+  test("undelegate with selector", 2, function() {
+    var counter1 = 0, counter2 = 0;
+    view.delegate('click', function() { counter1++; });
+    view.delegate('click', 'h1', function() { counter2++; });
+
+    view.undelegate('click', 'h1');
+
+    view.$('h1').trigger('click');
+    view.$el.trigger('click');
+
+    equal(counter1, 1);
+    equal(counter2, 0);
+  });
+
   test("_ensureElement with DOM node el", 1, function() {
     var View = Backbone.View.extend({
       el: document.body