如何从正在睡觉的WebSocket客户端计算机或应用程序转到后台恢复（iPad上的Safari）

I have browser client Javascript which opens a WebSocket (using socket.io) to request a long-running process start, and then gets a callback when the process is done. When I get the callback, I update the web page to let the user know the process has completed.I have browser client Javascript which opens a