Guseyn

function mapLimit (col, limit, mapFunc, doneFunc, newCol = [], index = { value: 0 }, freeThreads = { value: limit }) {
  if (freeThreads.value > 0 && index.value < col.length) {
    // Save current index
    const curIndex = index.value
    // Now the number of free threads is lower on 1
    freeThreads.value -= 1
    mapFunc((err, newItem) => {
      if (err) {
        // Smth bad happend, we call doneFunc with err

Guseyn

const assert = require('assert')

function flattenArray (nestedArray, resArray = []) {
  for (let i = 0; i < nestedArray.length; i++) {
    if (Array.isArray(nestedArray[i])) {
      flattenArray(nestedArray[i], resArray)
    } else {
      resArray.push(nestedArray[i])
    }
  }