promiseAll.js

function promiseAll(array) {
  let count = 0;
  const len = array.length;
  const result = new Array(len);
  return new Promise((resolve, reject) => {
    for (let index = 0; index < array.length; index++) {
      Promise.resolve(array[index]).then(
        (value) => {
          result[index] = value;
          count++;
          if (count === array.length) {
            resolve(result);
          }
        },
        (value) => {
          reject(value);
        }
      );
    }
  });
}

var p1 = new Promise((resolve, reject) => {
  setTimeout(resolve, 1000, "one");
});
var p2 = new Promise((resolve, reject) => {
  setTimeout(resolve, 2000, "two");
});
var p3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 3000, "three");
});
var p4 = new Promise((resolve, reject) => {
  setTimeout(resolve, 4000, "four");
});
var p5 = new Promise((resolve, reject) => {
  // reject('reject');
  setTimeout(resolve, 11, "5");
});

promiseAll([p1, p2, p3, p4, p5]).then(
  // Promise.all([p1, p2, p3, p4, p5]).then(
  (values) => {
    console.log(values);
  },
  (reason) => {
    console.log(reason);
  }
);