Polling implementation in Typescript

polling-typescript.ts

type Fn<T> = (payload: any) => T
type PromiseFn<T> = () => Promise<T>
type Options = {
 maxAttempts?: number,
 timeout?: number,
 delta?: number,
 validate?: Fn<boolean> | null,
}

/**
 * Polling implementation in Typescript
 * @param {PromiseFn} callback - The callback to execute
 * @param {Options} options - The options to configure the polling
 * @returns Promise<any>
 * @link {https://levelup.gitconnected.com/polling-in-javascript-ab2d6378705a}
 */
async function polling (callback: PromiseFn<any>, options: Options): Promise<any> {
  let attempts = 0
  const { maxAttempts = 10, timeout = 1000, delta = 1, validate = null } = options

  const executePoll = async (resolve: Fn<void>, reject: Fn<void>, ms = timeout) => {
    const result: any = await callback()
    const shouldResolve = validate?.(result)
    const maxAttemptsReached = attempts === maxAttempts
    
    attempts++

    if (shouldResolve) {
      return resolve(result)
    } else if (maxAttemptsReached) {
      if (!validate) {
        return resolve(result)
      } else {
        return reject(new Error('Exceeded max attempts'))
      }
    } else {
      setTimeout(executePoll, ms, resolve, reject, ms * delta)
    }
  }

  return new Promise(executePoll)
}

/**
 * Example
 * Get 3 jokes from the API of Chuck Norris
 */
async function getChuckNorrisJokes() {
  const jokes: any[] = []
  try {
    await polling(
      async () => {
        const { value } = await 
        	fetch("https://api.chucknorris.io/jokes/random")
        	.then(response => response.json())
        jokes.push(value)
      },
      { maxAttempts: 3, timeout: 1000, delta: 1, validate: null }
    )
  } catch(error) {
    console.log(error)
  } finally {
    // Should display after 3 seconds: ["joke 1...", "joke 2...", "joke 3..."]
    console.log(jokes)
  }
}

/**
 * Execute the example
 */
getChuckNorrisJokes()