fix(ngClass): add/remove classes which are properties of Object.prototype

Previously, ngClass and ngAnimate would track the status of classes using an ordinary object.
This causes problems when class names match names of properties in Object.prototype, including
non-standard Object.prototype properties such as 'watch' and 'unwatch' in Firefox. Because of
this shadowing, ngClass and ngAnimate were unable to correctly determine the changed status
of these classes.

In orderto accomodate this patch, some changes have been necessary elsewhere in the codebase,
in order to facilitate iterating, comparingand copying objects with a null prototype, or which
shadow the `hasOwnProperty` method

Summary:

- fast paths for various internal functions when createMap() is used
- Make createMap() safe for internal functions like copy/equals/forEach
- Use createMap() in more places to avoid needing hasOwnProperty()

Closes angular#11813

Author: caitp

src/Angular.js

@@ -36,6 +36,7 @@
   isUndefined: true,
   isDefined: true,
   isObject: true,
+  isBlankObject: true,
   isString: true,
   isNumber: true,
   isDate: true,
@@ -175,6 +176,7 @@ var
     splice            = [].splice,
     push              = [].push,
     toString          = Object.prototype.toString,
+    getPrototypeOf    = Object.getPrototypeOf,
     ngMinErr          = minErr('ng'),
 
     /** @name angular */
@@ -267,12 +269,25 @@ function forEach(obj, iterator, context) {
       }
     } else if (obj.forEach && obj.forEach !== forEach) {
         obj.forEach(iterator, context, obj);
-    } else {
+    } else if (isBlankObject(obj)) {
+      // createMap() fast path --- Safe to avoid hasOwnProperty check because prototype chain is empty
+      for (key in obj) {
+        iterator.call(context, obj[key], key, obj);
+      }
+    } else if (typeof obj.hasOwnProperty === 'function') {
+      // Slow path for objects inheriting Object.prototype, hasOwnProperty check needed
       for (key in obj) {
         if (obj.hasOwnProperty(key)) {
           iterator.call(context, obj[key], key, obj);
         }
       }
+    } else {
+      // Slow path for objects which do not have a method `hasOwnProperty`
+      for (key in obj) {
+        if (hasOwnProperty.call(obj, key)) {
+          iterator.call(context, obj[key], key, obj);
+        }
+      }
     }
   }
   return obj;
@@ -498,6 +513,16 @@ function isObject(value) {
 }
 
 
+/**
+ * Determine if a value is an object with a null prototype
+ *
+ * @returns {boolean} True if `value` is an `Object` with a null prototype
+ */
+function isBlankObject(value) {
+  return value !== null && typeof value === 'object' && !getPrototypeOf(value);
+}
+
+
 /**
  * @ngdoc function
  * @name angular.isString
@@ -781,7 +806,7 @@ function copy(source, destination, stackSource, stackDest) {
         destination = new RegExp(source.source, source.toString().match(/[^\/]*$/)[0]);
         destination.lastIndex = source.lastIndex;
       } else if (isObject(source)) {
-        var emptyObject = Object.create(Object.getPrototypeOf(source));
+        var emptyObject = Object.create(getPrototypeOf(source));
         destination = copy(source, emptyObject, stackSource, stackDest);
       }
     }
@@ -800,7 +825,7 @@ function copy(source, destination, stackSource, stackDest) {
       stackDest.push(destination);
     }
 
-    var result;
+    var result, key;
     if (isArray(source)) {
       destination.length = 0;
       for (var i = 0; i < source.length; i++) {
@@ -820,21 +845,40 @@ function copy(source, destination, stackSource, stackDest) {
           delete destination[key];
         });
       }
-      for (var key in source) {
-        if (source.hasOwnProperty(key)) {
-          result = copy(source[key], null, stackSource, stackDest);
-          if (isObject(source[key])) {
-            stackSource.push(source[key]);
-            stackDest.push(result);
+      if (isBlankObject(source)) {
+        // createMap() fast path --- Safe to avoid hasOwnProperty check because prototype chain is empty
+        for (key in source) {
+          putValue(key, source[key], destination, stackSource, stackDest);
+        }
+      } else if (source && typeof source.hasOwnProperty === 'function') {
+        // Slow path, which must rely on hasOwnProperty
+        for (key in source) {
+          if (source.hasOwnProperty(key)) {
+            putValue(key, source[key], destination, stackSource, stackDest);
+          }
+        }
+      } else {
+        // Slowest path --- hasOwnProperty can't be called as a method
+        for (key in source) {
+          if (hasOwnProperty.call(source, key)) {
+            putValue(key, source[key], destination, stackSource, stackDest);
           }
-          destination[key] = result;
         }
       }
       setHashKey(destination,h);
     }
-
   }
   return destination;
+
+  function putValue(key, val, destination, stackSource, stackDest) {
+    // No context allocation, trivial outer scope, easily inlined
+    var result = copy(val, null, stackSource, stackDest);
+    if (isObject(val)) {
+      stackSource.push(val);
+      stackDest.push(result);
+    }
+    destination[key] = result;
+  }
 }
 
 /**
@@ -915,14 +959,14 @@ function equals(o1, o2) {
       } else {
         if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2) ||
           isArray(o2) || isDate(o2) || isRegExp(o2)) return false;
-        keySet = {};
+        keySet = createMap();
         for (key in o1) {
           if (key.charAt(0) === '$' || isFunction(o1[key])) continue;
           if (!equals(o1[key], o2[key])) return false;
           keySet[key] = true;
         }
         for (key in o2) {
-          if (!keySet.hasOwnProperty(key) &&
+          if (!(key in keySet) &&
               key.charAt(0) !== '$' &&
               o2[key] !== undefined &&
               !isFunction(o2[key])) return false;

src/ng/animate.js

@@ -26,7 +26,9 @@ function splitClasses(classes) {
     classes = classes.split(' ');
   }
 
-  var obj = {};
+  // Use createMap() to prevent class assumptions involving property names in
+  // Object.prototype
+  var obj = createMap();
   forEach(classes, function(klass) {
     // sometimes the split leaves empty string values
     // incase extra spaces were applied to the options

src/ng/directive/ngClass.js

@@ -39,7 +39,9 @@ function classDirective(name, selector) {
         }
 
         function digestClassCounts(classes, count) {
-          var classCounts = element.data('$classCounts') || {};
+          // Use createMap() to prevent class assumptions involving property
+          // names in Object.prototype
+          var classCounts = element.data('$classCounts') || createMap();
           var classesToUpdate = [];
           forEach(classes, function(className) {
             if (count > 0 || classCounts[className]) {

test/AngularSpec.js

@@ -370,6 +370,21 @@ describe('angular', function() {
       expect(copy(undefined, [1,2,3])).toEqual([]);
       expect(copy({0: 1, 1: 2}, [1,2,3])).toEqual([1,2]);
     });
+
+    it('should copy objects with no prototype parent', function() {
+      var obj = extend(Object.create(null), {
+        a: 1,
+        b: 2,
+        c: 3
+      });
+      var dest = copy(obj);
+
+      expect(Object.getPrototypeOf(dest)).toBe(null);
+      expect(dest.a).toBe(1);
+      expect(dest.b).toBe(2);
+      expect(dest.c).toBe(3);
+      expect(Object.keys(dest)).toEqual(['a', 'b', 'c']);
+    });
   });
 
   describe("extend", function() {
@@ -651,6 +666,38 @@ describe('angular', function() {
     it('should return false when comparing an object and a Date', function() {
       expect(equals({}, new Date())).toBe(false);
     });
+
+    it('should safely compare objects with no prototype parent', function() {
+      var o1 = extend(Object.create(null), {
+        a: 1, b: 2, c: 3
+      });
+      var o2 = extend(Object.create(null), {
+        a: 1, b: 2, c: 3
+      });
+      expect(equals(o1, o2)).toBe(true);
+      o2.c = 2;
+      expect(equals(o1, o2)).toBe(false);
+    });
+
+
+    it('should safely compare objects which shadow Object.prototype.hasOwnProperty', function() {
+      /* jshint -W001 */
+      var o1 = {
+        hasOwnProperty: true,
+        a: 1,
+        b: 2,
+        c: 3
+      };
+      var o2 = {
+        hasOwnProperty: true,
+        a: 1,
+        b: 2,
+        c: 3
+      };
+      expect(equals(o1, o2)).toBe(true);
+      o1.hasOwnProperty = function() {};
+      expect(equals(o1, o2)).toBe(false);
+    });
   });
 
 
@@ -980,6 +1027,42 @@ describe('angular', function() {
     });
 
 
+    it('should safely iterate through objects with no prototype parent', function() {
+      var obj = extend(Object.create(null), {
+        a: 1, b: 2, c: 3
+      });
+      var log = [];
+      var self = {};
+      forEach(obj, function(val, key, collection) {
+        expect(this).toBe(self);
+        expect(collection).toBe(obj);
+        log.push(key + '=' + val);
+      }, self);
+      expect(log.length).toBe(3);
+      expect(log).toEqual(['a=1', 'b=2', 'c=3']);
+    });
+
+
+    it('should safely iterate through objects which shadow Object.prototype.hasOwnProperty', function() {
+      /* jshint -W001 */
+      var obj = {
+        hasOwnProperty: true,
+        a: 1,
+        b: 2,
+        c: 3
+      };
+      var log = [];
+      var self = {};
+      forEach(obj, function(val, key, collection) {
+        expect(this).toBe(self);
+        expect(collection).toBe(obj);
+        log.push(key + '=' + val);
+      }, self);
+      expect(log.length).toBe(4);
+      expect(log).toEqual(['hasOwnProperty=true', 'a=1', 'b=2', 'c=3']);
+    });
+
+
     describe('ES spec api compliance', function() {
 
       function testForEachSpec(expectedSize, collection) {

test/ng/directive/ngClassSpec.js

@@ -33,6 +33,32 @@ describe('ngClass', function() {
   }));
 
 
+  it('should add new and remove old classes with same names as Object.prototype properties dynamically', inject(function($rootScope, $compile) {
+    /* jshint -W001 */
+    element = $compile('<div class="existing" ng-class="dynClass"></div>')($rootScope);
+    $rootScope.dynClass = { watch: true, hasOwnProperty: true, isPrototypeOf: true };
+    $rootScope.$digest();
+    expect(element.hasClass('existing')).toBe(true);
+    expect(element.hasClass('watch')).toBe(true);
+    expect(element.hasClass('hasOwnProperty')).toBe(true);
+    expect(element.hasClass('isPrototypeOf')).toBe(true);
+
+    $rootScope.dynClass.watch = false;
+    $rootScope.$digest();
+    expect(element.hasClass('existing')).toBe(true);
+    expect(element.hasClass('watch')).toBe(false);
+    expect(element.hasClass('hasOwnProperty')).toBe(true);
+    expect(element.hasClass('isPrototypeOf')).toBe(true);
+
+    delete $rootScope.dynClass;
+    $rootScope.$digest();
+    expect(element.hasClass('existing')).toBe(true);
+    expect(element.hasClass('watch')).toBe(false);
+    expect(element.hasClass('hasOwnProperty')).toBe(false);
+    expect(element.hasClass('isPrototypeOf')).toBe(false);
+  }));
+
+
   it('should support adding multiple classes via an array', inject(function($rootScope, $compile) {
     element = $compile('<div class="existing" ng-class="[\'A\', \'B\']"></div>')($rootScope);
     $rootScope.$digest();