Asynchronous iterations

asyncLoop.js

/**
 * Asynchronous Loop
 * @param  {Int}
 * @param  {Function}
 * @param  {Function}
 * @return {Object}
 *
 *
 * Usage:
 *
 * asyncLoop(iterable.length, loop => {
 *  someAsyncFunction().then(data => {
 *    console.log(loop.index())
 *    loop.next()
 *  }).catch(error => throw error)
 * },
 * () => {
 *  console.log('Asynchronous Loop is done!')
 * })
 */
const asyncLoop = (iterations, func, callback) => {
  let i = 0
  let done = false
  let loop = {
    // Next loop iteration
    next () {
      if (done) return

      if (i < iterations) {
        i ++
        func(loop)
      } else {
        done = true
        callback()
      }
    },
    // Get loop index
    index () {
      return i - 1
    },
    // Break loop
    break () {
      done = true
      callback()
    }
  }
  // Start
  loop.next()
  return loop
}