类型：<number> 事件未被调度时返回 0，事件被调度时返回 2。
0
2
¥Type: <number> Returns 0 while an event is not being dispatched, 2 while it is being dispatched.
这在 Node.js 中没有使用，纯粹是为了完整性而提供的。
¥This is not used in Node.js and is provided purely for completeness.