nonced promise

nonced-promise.ts

import id from './generate-id'

export type NoncedEventPayload = {
  nonce: string
}

export type ParsedEventPayload = NoncedEventPayload & {
  value: string
  error: Error | null
}

export function createNoncedPromise<T extends ParsedEventPayload>(worker: Worker, payload: NoncedEventPayload) {
  const nonce = id(8)

  return new Promise<T>((resolve, reject) => {
    function onMessage(event: MessageEvent) {
      const data: T = event.data

      if (data.nonce !== nonce) return

      worker.removeEventListener('message', onMessage)

      if (data.error) {
        reject(data)
      } else {
        resolve(data)
      }
    }

    worker.addEventListener('message', onMessage)
    worker.postMessage(payload)
  })
}