Worker implementation for async functions

worker.js

class Worker {
  _stopped = false;
  _started = false;
  _onStop = noOp;

  constructor(channel, fn) {
    this._channel = channel;
    this._fn = fn;
  }

  setOnStop(cb) {
    this._onStop = cb;
  }

  async start() {
    if(this._started) {
      return;
    }
    this._stopped = false;
    while(!this._stopped) {
      const [exists, item, callback] = this._channel.next();
      if(!exists) {
        this._started = false;
        this._onStop(this);
        return;
      }
      try {
        callback({
          status: true,
          result: await this._fn(...item)
        });
      } catch(error) {
        callback({
          status: false,
          result: error,
        });
      }
    }
  }

  stop() {
    this._stopped = true;
  }
}