AngularJS save form before exit (both changing url or closing the window/tab)

saveBeforeExitDirective.js

angular.module('saveBeforeExitExample', [])
  .directive("saveBeforeExit", ["notificationService", function(notificationService) {
    "use strict";

    return {
      link: function(scope, element, attrs) {
        window.onbeforeunload = function(){
          if (element.hasClass("ng-dirty")) {
            element.submit();
          }
        };
        scope.$on("$locationChangeStart", function(event, next, current) {
          if (element.hasClass("ng-dirty")) {
            element.submit();
          }
        });
      }
    };
  }]);