webworker

webworker.ts

/**
 * example of worker (ex: worker.ts)
 *
 * ```ts
 * self.addEventListener('message', (event) => {
  const { eventName, data, messageId } = event.data;

  switch (eventName) {
    case 'double':
      const result = data * 2;
      self.postMessage({ eventName,messageId, result });
      break;
    case 'square':
      const squared = data * data;
      self.postMessage({ eventName,messageId, result: squared });
      break;
    default:
      self.postMessage({ eventName,messageId, error: 'Unknown event name' });
  }
});
`*``
 */
export class WebWorker<D extends object> {
  constructor(readonly worker: Worker) {}

  uuid(): string {
      try {
          return crypto.randomUUID();
      } catch (err) {
          return `${Date.now()}`;
      }
  }

  sendMessageToWorker<R = any, K extends keyof D = keyof D>(
      eventName: K,
      data?: D[K],
      timeout = 5e3
  ): Promise<R> {
      return new Promise((resolve, reject) => {
          const messageId = `${eventName as string}-${this.uuid()}`;

          let timer: NodeJS.Timeout;

          const handleMessage = (event: MessageEvent) => {
              if (
                  event.data.eventName === eventName &&
                  event.data.messageId === messageId
              ) {
                  clearTimeout(timer);

                  this.worker.removeEventListener('message', handleMessage);

                  if (event.data.error) {
                      reject(new Error(event.data.error));
                  } else {
                      resolve(event.data.result);
                  }
              }
          };

          this.worker.addEventListener('message', handleMessage);

          if (timeout && timeout > 0) {
              timer = setTimeout(() => {
                  this.worker.removeEventListener('message', handleMessage);

                  reject(
                      new Error(
                          `Timeout: No response for event "${eventName as string}" within ${timeout}ms`
                      )
                  );
              }, timeout);
          }

          this.worker.postMessage({ eventName, data, messageId });
      });
  }
}