short circuit promises in Nodejs

short-circuit-promises.ts

import axios, { AxiosResponse } from 'axios'

type TODO = {
  userId: number
  id: number
  title: string
  completed: boolean
}

const DEFAULT_TIMEOUT = 200

const DEFAULT_TODO: TODO = {
  userId: 1,
  id: 2,
  title: 'DEFAULT_TITLE',
  completed: false,
}

const fetchData = async (): Promise<AxiosResponse<TODO>> => {
  await new Promise((resolve) => setTimeout(resolve, DEFAULT_TIMEOUT + 1))
  return axios.get<TODO>('https://jsonplaceholder.typicode.com/todos/1')
}

const timeout = async () => {
  await new Promise((resolve) => setTimeout(resolve, DEFAULT_TIMEOUT))
  return Promise.reject(DEFAULT_TODO)
}

const main = async () => {
  const promises = [
    fetchData(),
    fetchData(),
    fetchData(),
    fetchData(),
    fetchData(),
    fetchData(),
    timeout(),
  ]
  const finalData = await Promise.race(promises)
    .then((response) => response.data)
    .catch(() => DEFAULT_TODO)
  return finalData
}

main().then(console.log)

Promise.race()
Settles when any of the promises settles. In other words, fulfills when any of the promises fulfills; rejects when any of the promises rejects.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/race

a nice package, but it does not work with multiple promises out of the box

https://www.npmjs.com/package/opossum

also checkout this

HTTP request orchestration techniques

https://github.com/Rowadz/promise-queue-concurrency-control

https://youtube.com/playlist?list=PLM0LBHjz37LWlkONmhzkAdd2CS_HqKjep&si=AvYIXaqvGTz2V--r