event bubbling

基本解釋

Also, (not sure about this) i think your script will fire twice because of the event bubbling.
同時，（這個不確定）我覺得你的腳本將火兩次因為事件冒泡。
The event bubbling technique provides the ability to disconnect the view structure of the widget from the controller code.
事件氣泡技巧可用于斷開小組件的視圖結(jié)構(gòu)與控制器代碼之間的連接。
For more information about the difference between canceling event bubbling and canceling the default action on an event, see About the DHTML Object Model.
如需在事件上有關(guān)取消事件反升與取消預(yù)設(shè)動作之間差異的詳細(xì)資訊，請參閱關(guān)于 DHTML 物件模型（英文）。