事件:'message'
¥Event: 'message'
为任何传入消息触发 'message' 事件,其中包含 port.postMessage() 的克隆输入。
¥The 'message' event is emitted for any incoming message, containing the cloned
input of port.postMessage().
此事件的监听器接收传给 postMessage() 的 value 参数的副本,没有其他参数。
¥Listeners on this event receive a clone of the value parameter as passed
to postMessage() and no further arguments.