事件:'message'
🌐 Event: 'message'
value<any> 传输的值
'message' 事件会在收到任何消息时触发,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().
该事件的监听器会接收到 postMessage() 传入的 value 参数的副本,而不会接收其他任何参数。
🌐 Listeners on this event receive a clone of the value parameter as passed
to postMessage() and no further arguments.