Method onMessage

packages/service-worker/worker/src/driver.ts:298–329

* The handler for message events.

(event: ExtendableMessageEvent)

   * The handler for message events.
   */
  private onMessage(event: ExtendableMessageEvent): void {
    // Ignore message events when the SW is in safe mode, for now.
    if (this.state === DriverReadyState.SAFE_MODE) {
      return;
    }

    // If the message doesn't have the expected signature, ignore it.
    const data = event.data;
    if (!data || !data.action) {
      return;
    }

    event.waitUntil(
      (async () => {
        // Initialization is the only event which is sent directly from the SW to itself, and thus
        // `event.source` is not a `Client`. Handle it here, before the check for `Client` sources.
        if (data.action === 'INITIALIZE') {
          return this.ensureInitialized(event);
        }

        // Only messages from true clients are accepted past this point.
        // This is essentially a typecast.
        if (!this.adapter.isClient(event.source)) {
          return;
        }

        // Handle the message and keep the SW alive until it's handled.
        await this.ensureInitialized(event);
        await this.handleMessage(data, event.source);
      })(),
    );
  }

  private onPush(msg: PushEvent): void {
    // Push notifications without data have no effect.