AngularJS Rollback value with ng-change

ngchange_rollback.js

$scope.$watch('color', function(newValue, oldValue) { 
    $scope.previousColor = oldValue;
});

$scope.changeColor = function(){
  $http.put('...', {color:  $scope.color}).error(function(){
    $scope.color =  $scope.previousColor;
  });   
};