观看多个$ scope属性

从AngularJS
1.3开始，有一个新方法称为

$watchGroup

$scope.foo = 'foo';$scope.bar = 'bar';$scope.$watchGroup(['foo', 'bar'], function(newValues, oldValues, scope) {  // newValues array contains the current values of the watch expressions  // with the indexes matching those of the watchexpression array  // i.e.  // newValues[0] -> $scope.foo   // and   // newValues[1] -> $scope.bar });