chromium/third_party/blink/web_tests/external/wpt/wasm/serialization/module/resources/broadcastchannel-sharedworker.js

const channel = new BroadcastChannel("anne was here");
channel.onmessageerror = ({ data }) => {
  if(data === null) {
    channel.postMessage("sw-success");
  }
}
channel.postMessage("hi");