whisper.cat/weboasis/arcade/zombie2/offlineClient.js
2023-10-05 23:28:32 +11:00

54 lines
1.4 KiB
JavaScript

"use strict";
(function() {
class OfflineClient
{
constructor()
{
// Create a BroadcastChannel, if supported.
this._broadcastChannel = (typeof BroadcastChannel === "undefined" ? null : new BroadcastChannel("offline"));
// Queue of messages received before a message callback is set.
this._queuedMessages = [];
// The message callback.
this._onMessageCallback = null;
// If BroadcastChannel is supported, listen for messages.
if (this._broadcastChannel)
this._broadcastChannel.onmessage = (e => this._OnBroadcastChannelMessage(e));
}
_OnBroadcastChannelMessage(e)
{
// Have a message callback set: just forward the call.
if (this._onMessageCallback)
{
this._onMessageCallback(e);
return;
}
// Otherwise the app hasn't loaded far enough to set a message callback.
// Buffer the incoming messages to replay when the app sets a callback.
this._queuedMessages.push(e);
}
SetMessageCallback(f)
{
this._onMessageCallback = f;
// Replay any queued messages through the handler, then clear the queue.
for (let e of this._queuedMessages)
this._onMessageCallback(e);
this._queuedMessages.length = 0;
}
};
// Create the offline client ASAP so we receive and start queueing any messages the SW broadcasts.
window.OfflineClientInfo = new OfflineClient();
}());