demo · v140

SharedWorker probe + counter

Detect SharedWorker support on this device. If it's available, the demo spins one up and shares a counter across all tabs of this origin — open this URL in a second tab to watch the count tick in sync.

—

Worker event log:

(initialising)

const w = new SharedWorker(URL.createObjectURL(new Blob([`
  let count = 0;
  const ports = [];
  onconnect = (e) => {
    const port = e.ports[0];
    ports.push(port);
    port.onmessage = (m) => {
      if (m.data === "inc") count++;
      else if (m.data === "reset") count = 0;
      ports.forEach(p => p.postMessage(count));
    };
    port.postMessage(count);
  };
`])));

see also