event.composedPath()
返回包含当前 EventTarget
作为唯一条目的数组,如果未调度事件则返回空数组。
这在 Node.js 中没有使用,纯粹是为了完整性而提供的。
Returns an array containing the current EventTarget
as the only entry or
empty if the event is not being dispatched. This is not used in
Node.js and is provided purely for completeness.