是否有针对返回值为addEventListener回调的解决方案?

AddEventListener按规范不返回值,也不会返回值。如果AddEventListener要返回一个值,那么它将是无用的,因为触发回调函数的事件将获取返回值,而不是仅注册它的AddEventListener。

addEventListener( 'onload', function() {

  // do something

  return true;

  // bool(true) would be returned to window.event[onload] and not to addEventListener if that were the case which would still make it useless to you.

}, false );

这么说,有一个肮脏的方法,但它应该得到你想要的。

var eventTracker = {

  retVal: false,

  retEvt: false,

  trigger: function( e ) {

    e = e || window.event;

    // some code here
  }

};

function someFn(e) {

  e = e || window.event;

  // Some code here

  eventTracker.retVal = true;

  eventTracker.retEvt = e.type;

  eventTracker.trigger.call( e );

}

// Bind the event in all browsers
if ( window.addEventListener ) {
    window.addEventListener( 'load', someFn, false );
} else if ( window.attachEvent ) {
    window.attachEvent( 'onload', someFn );
} else {
    window.onload = someFn;
}