TypeScript angular 1.5 filter

MarkSelectedFilter.ts

/**
   * Wraps a match inside a string between <b>...</b> tags
   * 
   * Example:
   *   $filter('filtername').('match');
   * 
   * Note: make sure you'll render this using ng-bind-html (in a repeater you'll probably must use ng-if as well, or otherwise all nodes will be rendered (empty when no match))
   */
  class MarkSelectedFilter {
    
    public static factory() {
      let factory = ($sce: ng.ISCEService) => {
        return (input: string, match: string)  => {
          let regex = new RegExp(`(${match})`, 'gi');
          if (regex.test(input)) {
           return $sce.trustAsHtml(input.replace(regex, '<b>$1</b>'));
          }
          return null;
        }
      };
      factory.$inject = ['$sce'];
      return factory;
    }
  }