Renamed wheel service to mousewheel and added it's tests

Closes #18

Author: joelmukuthu

src/directives/snapscroll.js

@@ -86,15 +86,17 @@
     });
   };
 
-  var initWheelEvents = function (wheel, scope, element) {
+  var initWheelEvents = function (mousewheel, scope, element) {
     function maybePreventBubbling(e, bubbleUp) {
       if (!bubbleUp) {
         e.stopPropagation();
       }
     }
 
-    wheel.bind(element, {
+    mousewheel.bind(element, {
       up: function (e) {
+        e.preventDefault();
+
         var bubbleUp;
         if (scope.snapDirection !== 'down') {
           if (scope.snapIndex - 1 < scope.snapIndexMin()) {
@@ -106,9 +108,12 @@
             });
           }
         }
+
         maybePreventBubbling(e, bubbleUp);
       },
       down: function (e) {
+        e.preventDefault();
+
         var bubbleUp;
         if (scope.snapDirection !== 'up') {
           if (scope.snapIndex + 1 > scope.scopeIndexMax()) {
@@ -120,17 +125,18 @@
             });
           }
         }
+
         maybePreventBubbling(e, bubbleUp);
       }
     });
 
     scope.$on('$destroy', function () {
-      wheel.unbind(element);
+      mousewheel.unbind(element);
     });
   };
 
-  var snapscrollAsAnAttribute = ['$timeout', 'scroll', 'wheel', 'defaultSnapscrollScrollDelay', 'defaultSnapscrollSnapDuration', 'defaultSnapscrollBindScrollTimeout',
-    function ($timeout, scroll, wheel, defaultSnapscrollScrollDelay, defaultSnapscrollSnapDuration, defaultSnapscrollBindScrollTimeout) {
+  var snapscrollAsAnAttribute = ['$timeout', 'scroll', 'mousewheel', 'defaultSnapscrollScrollDelay', 'defaultSnapscrollSnapDuration', 'defaultSnapscrollBindScrollTimeout',
+    function ($timeout, scroll, mousewheel, defaultSnapscrollScrollDelay, defaultSnapscrollSnapDuration, defaultSnapscrollBindScrollTimeout) {
       return {
         restrict: 'A',
         scope: scopeObject,
@@ -271,7 +277,7 @@
               scope.$on('$destroy', unbindScroll);
             }
 
-            initWheelEvents(wheel, scope, element);
+            initWheelEvents(mousewheel, scope, element);
           };
 
           init();

src/services/wheel.js renamed to src/services/mousewheel.js

@@ -3,29 +3,45 @@
 
   var snapscroll = angular.module('snapscroll');
 
-  snapscroll.factory('wheel', [function () {
+  snapscroll.factory('mousewheel', [function () {
     function onWheel(e, up, down) {
       var delta;
 
       if (e.originalEvent) {
         e = e.originalEvent;
       }
-      e.preventDefault();
 
       delta = Math.max(-1, Math.min(1, (e.wheelDelta || -(e.deltaY || e.detail))));
       if (isNaN(delta) || delta === 0) {
         return;
       }
 
-      if (delta < 0) {
-        down(e);
+      if (delta > 0) {
+        if (up) {
+          up(e);
+        }
       } else {
-        up(e);
+        if (down) {
+          down(e);
+        }
       }
     }
 
     return {
       bind: function (element, callbacks) {
+        callbacks = callbacks || {};
+        if (angular.isDefined(callbacks.up) && !angular.isFunction(callbacks.up)) {
+          throw new Error('The \'up\' callback must be a function');
+        }
+
+        if (angular.isDefined(callbacks.down) && !angular.isFunction(callbacks.down)) {
+          throw new Error('The \'down\' callback must be a function');
+        }
+
+        if (!angular.isDefined(callbacks.up) && !angular.isDefined(callbacks.down)) {
+          throw new Error('At least one callback (\'up\' or \'down\') must be provided');
+        }
+
         function bindWheel(e) {
           onWheel(e, callbacks.up, callbacks.down);
         }
@@ -35,7 +51,7 @@
 
       unbind: function (element) {
         var bindWheel = element.data('snapscroll-bindWheel');
-        if (bindWheel) {
+        if (angular.isFunction(bindWheel)) {
           element.data('snapscroll-bindWheel', null);
           element.off('wheel mousewheel onmousewheel', bindWheel);
         }

test/spec/directives/snapscroll.js

@@ -158,16 +158,25 @@ describe('Directive: snapscroll', function () {
     element = compileElement(html, true);
     element.triggerHandler({
       type: 'wheel',
+      wheelDelta: -120,
+      detail: 120,
+      deltaY: 120,
       preventDefault: preventDefault
-    });
+    }); // mousewheel down
     element.triggerHandler({
       type: 'mousewheel',
+      wheelDelta: 120,
+      detail: -120,
+      deltaY: -120,
       preventDefault: preventDefault
-    });
+    }); // mousewheel up
     element.triggerHandler({
       type: 'onmousewheel',
+      wheelDelta: -120,
+      detail: 120,
+      deltaY: 120,
       preventDefault: preventDefault
-    });
+    }); // mousewheel down
     expect(preventDefault).toHaveBeenCalled();
     expect(preventDefault.calls.count()).toBe(3);
   }