custom asynchronous filter to format date into appropriate format

formattedDate.filter.js

(function() {
  'use strict';

  angular
    .module('app.directives')

  /**
   * @ngdoc filter
   * @name filter:formattedDate
   * @description
   * filter to return in formatted time format
   * @function
   * @requires $translate
   * @requires dateFilter
  */
    .filter('formattedDate', function(dateFilter, $translate) {

      var format = null, translated = false;

      function returnFilter(inputDate) {
        if(format){
          return dateFilter(inputDate, format);
        }else{
          return '-';
        }
      }

      function formattedDateFilter(inputDate){
        if( format === null ) {
          if( !translated ){
            translated = true;
            // it is GENERAL.TIME_FORMAT is coming from one of translations 
            // It can have format as dd/MM/yyyy HH:mm for english
            //or any other format for any other language
            $translate('GENERAL.TIME_FORMAT').then(function (result) { 
              format = result;
            },function (translationId) {
              format = translationId;
            });
          }
          
        }
        else return returnFilter(inputDate); 
      }

      formattedDateFilter.$stateful = true;
      return formattedDateFilter;
    });

})();