Add isDate method + fix old code

src/Angular.js

@@ -317,6 +317,7 @@ function isDefined(value){ return typeof value != $undefined; }
 function isObject(value){ return value!=_null && typeof value == $object;}
 function isString(value){ return typeof value == $string;}
 function isNumber(value){ return typeof value == $number;}
+function isDate(value){ return value instanceof Date; }
 function isArray(value) { return value instanceof Array; }
 function isFunction(value){ return typeof value == $function;}
 function isBoolean(value) { return typeof value == $boolean;}
@@ -431,7 +432,7 @@ function copy(source, destination){
     if (source) {
       if (isArray(source)) {
         destination = copy(source, []);
-      } else if (source instanceof Date) {
+      } else if (isDate(source)) {
         destination = new Date(source.getTime());
       } else if (isObject(source)) {
         destination = copy(source, {});

src/JSON.js

@@ -72,7 +72,7 @@ function toJsonArray(buf, obj, pretty, stack) {
         sep = true;
       }
       buf.push("]");
-    } else if (obj instanceof Date) {
+    } else if (isDate(obj)) {
       buf.push(angular['String']['quoteUnicode'](angular['Date']['toString'](obj)));
     } else {
       buf.push("{");

src/apis.js

@@ -4,7 +4,7 @@ var angularGlobal = {
     var type = typeof obj;
     if (type == $object) {
       if (obj instanceof Array) return $array;
-      if (obj instanceof Date) return $date;
+      if (isDate(obj)) return $date;
       if (obj.nodeType == 1) return $element;
     }
     return type;

src/filters.js

@@ -199,7 +199,9 @@ angularFilter.date = function(date, format) {
 
   if (isNumber(date)) {
     date = new Date(date);
-  } else if (!(date instanceof Date)) {
+  }
+
+  if (!isDate(date)) {
     return date;
   }
 

test/AngularSpec.js

@@ -328,3 +328,16 @@ describe('angular service', function() {
     expect(result.third).toBeTruthy();
   });
 });
+
+describe('isDate', function() {
+  it('should return true for Date object', function() {
+    expect(isDate(new Date())).toBe(true);
+  });
+
+  it('should return false for non Date objects', function() {
+    expect(isDate([])).toBe(false);
+    expect(isDate('')).toBe(false);
+    expect(isDate(23)).toBe(false);
+    expect(isDate({})).toBe(false);
+  });
+});