Worker Sync XHR

Proof that even if an XHR is sent in a Web Worker (synchronously), it never gets sent while the main thread is blocked.

Online at: https://azriel.im/worker_sync_xhr/

Output:

21:45:04.769 main: creating worker
21:45:04.828 worker: created
21:45:06.498 ---
21:45:06.504 main (sync): sending message to worker
21:45:06.505 main (sync): wait begin
21:45:08.045 main (sync): wait end
21:45:08.047 worker: request begin
21:45:08.054 worker: request end
21:45:11.884 ---
21:45:11.888 main (async): sending message to worker
21:45:11.889 main (async): wait begin
21:45:11.896 worker: request begin
21:45:11.968 worker: request end
21:45:12.891 main (async): wait end

Logic

main:

1. Start worker.
2. Log begin.
3. Wait 1.5 seconds.
4. Log end.

worker:

1. Log begin.
2. Send XHR synchronously.
3. Log end.

Running Locally

1. Start a HTTP server in the repository directory:

   python -m SimpleHTTPServer 8000

2. Open http://localhost:8000/.

3. Look at the console log.

4. Edit index.html.

5. Refresh the page.