promise.all in javascript mdn code example

Example 1: Promise.all

const promise1 = Promise.resolve(3);
const promise2 = 42;
const promise3 = new Promise(function(resolve, reject) {
  setTimeout(resolve, 100, 'foo');
});

Promise.all([promise1, promise2, promise3]).then(function(values) {
  console.log(values);
});
// expected output: Array [3, 42, "foo"]

Example 2: promise.all

// A simple promise that resolves after a given time
const timeOut = (t) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve(`Completed in ${t}`)
    }, t)
  })
}

// Resolving a normal promise.
timeOut(1000)
 .then(result => console.log(result)) // Completed in 1000

// Promise.all
Promise.all([timeOut(1000), timeOut(2000)])
 .then(result => console.log(result)) // ["Completed in 1000", "Completed in 2000"]