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