$transition = function(element, trigger, options) {
    options = options || {};
    var deferred = $q.defer();
    var endEventName = $transition[options.animation ? "animationEndEventName" : "transitionEndEventName"];

    var transitionEndHandler = function(event) {
      $rootScope.$apply(function() {
        element.unbind(endEventName, transitionEndHandler);
        deferred.resolve(element);
      });
    };

    if (endEventName) {
      element.bind(endEventName, transitionEndHandler);
    }

    // Wrap in a timeout to allow the browser time to update the DOM before the transition is to occur
    $timeout(function() {
      if ( angular.isString(trigger) ) {
        element.addClass(trigger);
      } else if ( angular.isFunction(trigger) ) {
        trigger(element);
      } else if ( angular.isObject(trigger) ) {
        element.css(trigger);
      }
      //If browser does not support transitions, instantly resolve
      if ( !endEventName ) {
        deferred.resolve(element);
      }
    });

    // Add our custom cancel function to the promise that is returned
    // We can call this if we are about to run a new transition, which we know will prevent this transition from ending,
    // i.e. it will therefore never raise a transitionEnd event for that transition
    deferred.promise.cancel = function() {
      if ( endEventName ) {
        element.unbind(endEventName, transitionEndHandler);
      }
      deferred.reject('Transition cancelled');
    };

    return deferred.promise;
  }
$transition service provides a consistent interface to trigger CSS 3 transitions and to be informed when they complete.
@param  {DOMElement} element  The DOMElement that will be animated.
@param  {string|object|function} trigger  The thing that will cause the transition to start:
  - As a string, it represents the css class to be added to the element.
  - As an object, it represents a hash of style attributes to be applied to the element.
  - As a function, it represents a function to be called that will cause the transition to occur.
@return {Promise}  A promise that is resolved when the transition finishes.