gistfile1.txt

let gListenersFR = new FinalizationRegistry(
  ({ socket, wrapper }) => socket.removeEventListener('message', wrapper));
  
class EventAccumulator {
  constructor(socket) {
    this.events = [];
    this.listener = (ev) => { this.events.push(ev); };
    let weakRef = new WeakRef(this.listener);
    let wrapper = (ev) => { weakRef.deref()?.(ev); };
    socket.addEventListener('message', wrapper);
    gListenersFR.register(this.listener, { socket, wrapper });
  }
}

// Intended use is that when EventAccumulator dies, no need to manually
// unregister the event listener on socket, everything takes care of
// itself.