Function addEvent

tests/qunit/qunit.js:3171–3188

* @param {HTMLElement} elem * @param {string} type * @param {Function} fn

( elem, type, fn )

   * @param {Function} fn
   */
  function addEvent( elem, type, fn ) {
    if ( elem.addEventListener ) {

      // Standards-based browsers
      elem.addEventListener( type, fn, false );
    } else if ( elem.attachEvent ) {

      // support: IE <9
      elem.attachEvent( "on" + type, function() {
        var event = window.event;
        if ( !event.target ) {
          event.target = event.srcElement || document;
        }

        fn.call( elem, event );
      });
    }
  }

  /**
   * @param {Array|NodeList} elems