Add class as an alias of css. This allows for combined static and dyn…

…amic class bindings.

spec/defaultBindings/cssBehaviors.js

@@ -102,4 +102,31 @@ describe('Binding: CSS classes', function() {
         observable1("my-Rule");
         expect(testNode.childNodes[0].className).toEqual("unrelatedClass1 my-Rule");
     });
+
+    it('Should be aliased as class as well as css', function() {
+        expect(ko.bindingHandlers['class']).toEqual(ko.bindingHandlers.css);
+    });
+
+    it('Should be able to combine "class" and "css" bindings with dynamic and static classes', function () {
+        // This test doesn't cover cases where the static and dynamic bindings try to set or unset the same class name
+        // because the behavior for that scenario isn't defined.
+
+        var booleanProp = new ko.observable(false);
+        var stringProp = new ko.observable("");
+        testNode.innerHTML = "<div class='unrelatedClass' data-bind='css: { staticClass: booleanProp }, class: stringProp'></div>";
+
+        ko.applyBindings({ booleanProp: booleanProp, stringProp: stringProp }, testNode);
+        expect(testNode.childNodes[0].className).toEqual("unrelatedClass");
+
+        booleanProp(true);
+        expect(testNode.childNodes[0].className).toEqual("unrelatedClass staticClass");
+
+        stringProp("dynamicClass");
+        expect(testNode.childNodes[0].className).toEqual("unrelatedClass staticClass dynamicClass");
+
+        booleanProp(false);
+        expect(testNode.childNodes[0].className).toEqual("unrelatedClass dynamicClass");
+        stringProp(null);
+        expect(testNode.childNodes[0].className).toEqual("unrelatedClass");
+    });
 });

src/binding/defaultBindings/css.js

@@ -1,5 +1,5 @@
 var classesWrittenByBindingKey = '__ko__cssValue';
-ko.bindingHandlers['css'] = {
+ko.bindingHandlers['class'] = ko.bindingHandlers['css'] = {
     'update': function (element, valueAccessor) {
         var value = ko.utils.unwrapObservable(valueAccessor());
         if (value !== null && typeof value == "object") {