2 files changed, 10 insertions, 56 deletions
diff --git a/src/directives.js b/src/directives.js
index 6fc19eaf..d800aa80 100644
--- a/src/directives.js
+++ b/src/directives.js
@@ -565,25 +565,18 @@ angularDirective("ng:submit", function(expression, element) {
   });
 });
 
+
 function ngClass(selector) {
   return function(expression, element){
+    var existing = element[0].className + ' ';
     return function(element){
-      if(selector(this.$index)) {
-        this.$watch(expression, function(newCls, oldCls) {
-          var cls = element.attr('class');
-          if (isArray(newCls)) newCls = newCls.join(' ');
-          if (isArray(oldCls)) oldCls = oldCls.join(' ');
-
-          // The time when newCls == oldCLs is when $watch just started
-          if (newCls == oldCls) {
-            cls += ' ' + newCls;
-          } else {
-            cls = cls.replace(' ' + oldCls, ' ' + newCls);
-          }
-
-          element.attr('class', cls);
-        });
-      }
+      this.$onEval(function(){
+        if (selector(this.$index)) {
+          var value = this.$eval(expression);
+          if (isArray(value)) value = value.join(' ');
+          element[0].className = trim(existing + value);
+        }
+      }, element);
     };
   };
 }
diff --git a/test/directivesSpec.js b/test/directivesSpec.js
index 39c52ac6..bb530128 100644
--- a/test/directivesSpec.js
+++ b/test/directivesSpec.js
@@ -179,7 +179,7 @@ describe("directive", function(){
 
 
   describe('ng:class', function() {
-    it('should change current class or remove old classes dynamically', function() {
+    it('should add new and remove old classes dynamically', function() {
       var scope = compile('<div class="existing" ng:class="dynClass"></div>');
       scope.dynClass = 'A';
       scope.$eval();
@@ -206,45 +206,6 @@ describe("directive", function(){
       expect(element.hasClass('A')).toBeTruthy();
       expect(element.hasClass('B')).toBeTruthy();
     });
-
-    it('should preserve class added post compilation', function() {
-      var scope = compile('<div class="existing" ng:class="dynClass"></div>');
-      scope.dynClass = 'A';
-      scope.$eval();
-      expect(element.hasClass('existing')).toBe(true);
-
-      // add extra class, change model and eval
-      element.addClass('newClass');
-      scope.dynClass = 'B';
-      scope.$eval();
-
-      expect(element.hasClass('existing')).toBe(true);
-      expect(element.hasClass('B')).toBe(true);
-      expect(element.hasClass('newClass')).toBe(true);
-    });
-
-    it('should preserve class added post compilation even without existing classes"', function() {
-      var scope = compile('<div ng:class="dynClass"></div>');
-      scope.dynClass = 'A';
-      scope.$eval();
-      expect(element.hasClass('A')).toBe(true);
-
-      // add extra class, change model and eval
-      element.addClass('newClass');
-      scope.dynClass = 'B';
-      scope.$eval();
-
-      expect(element.hasClass('B')).toBe(true);
-      expect(element.hasClass('newClass')).toBe(true);
-    });
-
-    it('should preserve right classes"', function() {
-      var scope = compile('<div class="ui-panel ui-selected" ng:class="dynCls"></div>');
-      scope.dynCls = 'panel';
-      scope.dynCls = 'foo';
-      scope.$eval();
-      expect(element.attr('class')).toBe('ui-panel ui-selected ng-directive foo');
-    });
   });