promises demo

promise.js

'use strict';

function coinFlip(delay) {
  return new Promise((resolve, reject) => {
    setTimeout(function () {
      if (Math.round(Math.random())) {
        resolve('Heads!');
      } else {
        reject('Tails!');
      }
    }, delay);
  });
}

const coin1 = coinFlip(100).catch(err => err);
const coin2 = coinFlip(200).catch(err => err);
const coin3 = coinFlip(300).catch(err => err);

Promise.all( [coin1, coin2, coin3] )
  .then(arrayOfResults => {
    console.log(arrayOfResults);
  })
  .catch(err => {
    console.error(err);
  });


coinFlip(500)
  .then(res => {
    console.log(1, res);
    return coinFlip(250);
  })
  .then(res => {
    console.log(2, res);
    return coinFlip(750);
  })
  .then(res => {
    console.log(3, res);
    return 'You Win!';
  })
  .then(res => {
    console.log(4, res);
  })
  .catch(err => {
    console.error(err);
  });