ES6 Promise replacement of async.eachLimit / async.mapLimit

Question

In async, if I need to apply a asynchronousfunction to 1000 items, I can do that with:

async.mapLimit(items, 10, (item, callback) => {
    foo(item, callb         


        

Answer 1

This is the closest one to async.eachLimit

Promise.eachLimit = async (coll, limit, asyncFunc) => {
let ret = [];
    const splitArr = coll.reduce((acc,item,i)=> (i%limit) ? acc :[...acc,coll.slice(i,i+limit)],[])
    for(let i =0; i< splitArr.length;i++){
        ret[i]=await Promise.all(splitArr[i].map(ele=>asyncFunc(ele)));
    }
    return ret;
}

const wait = ms => new Promise(resolve => setTimeout(resolve, ms));

async function foo(s) {
  await wait(Math.random() * 2000);
  console.log(s);
  return s.toLowerCase();
}

(async () => {
  let arr = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".split("");
  console.log((await Promise.eachLimit(arr, 5, foo)));
})();