feat(jqLite): provide support for element.one()

Author: matsko

src/jqLite.js

@@ -54,6 +54,7 @@
  * - [`next()`](http://api.jquery.com/next/) - Does not support selectors
  * - [`on()`](http://api.jquery.com/on/) - Does not support namespaces, selectors or eventData
  * - [`off()`](http://api.jquery.com/off/) - Does not support namespaces or selectors
+ * - [`one()`](http://api.jquery.com/one/) - Does not support namespaces or selectors
  * - [`parent()`](http://api.jquery.com/parent/) - Does not support selectors
  * - [`prepend()`](http://api.jquery.com/prepend/)
  * - [`prop()`](http://api.jquery.com/prop/)
@@ -744,6 +745,19 @@ forEach({
 
   off: jqLiteOff,
 
+  one: function(element, type, fn) {
+    element = jqLite(element);
+
+    //add the listener twice so that when it is called
+    //you can remove the original function and still be
+    //able to call element.off(ev, fn) normally
+    element.on(type, function onFn() {
+      element.off(type, fn);
+      element.off(type, onFn);
+    });
+    element.on(type, fn);
+  },
+
   replaceWith: function(element, replaceNode) {
     var index, parent = element.parentNode;
     jqLiteDealoc(element);

test/jqLiteSpec.js

@@ -1177,6 +1177,63 @@ describe('jqLite', function() {
     }
   });
 
+  describe('one', function() {
+
+    it('should only fire the callback once', function() {
+      var element = jqLite(a);
+      var spy = jasmine.createSpy('click');
+
+      element.one('click', spy);
+
+      browserTrigger(element, 'click');
+      expect(spy).toHaveBeenCalledOnce();
+
+      browserTrigger(element, 'click');
+      expect(spy).toHaveBeenCalledOnce();
+    });
+
+    it('should deregister when off is called', function() {
+      var element = jqLite(a);
+      var spy = jasmine.createSpy('click');
+
+      element.one('click', spy);
+      element.off('click', spy);
+
+      browserTrigger(element, 'click');
+      expect(spy).not.toHaveBeenCalled();
+    });
+
+    it('should return the same event object just as on() does', function() {
+      var element = jqLite(a);
+      var eventA, eventB;
+      element.on('click', function(event) {
+        eventA = event;
+      });
+      element.one('click', function(event) {
+        eventB = event;
+      });
+
+      browserTrigger(element, 'click');
+      expect(eventA).toEqual(eventB);
+    });
+
+    it('should not remove other event handlers of the same type after execution', function() {
+      var element = jqLite(a);
+      var calls = [];
+      element.one('click', function(event) {
+        calls.push('one');
+      });
+      element.on('click', function(event) {
+        calls.push('on');
+      });
+
+      browserTrigger(element, 'click');
+      browserTrigger(element, 'click');
+
+      expect(calls).toEqual(['one','on','on']);
+    });
+  });
+
 
   describe('replaceWith', function() {
     it('should replaceWith', function() {