Playing with Promises

promise.js

'use strict';

console.log('starting promise.js');

console.time('A');

function asyncFunc() {
  return new Promise(
    function (resolve, reject) {
      console.log(1);
      resolve('success value'); // success
      console.log(2);
      reject('error value'); // failure
    });
}

let async1 = asyncFunc()
  .then(value => {
    /* success */
    console.log(3);
    console.log('success:',value);
  })
  .catch(error => {
    /* failure */
    console.log(4);
    console.log('failure:',error);
  });

function delay(ms) {
  console.log(5);
  return new Promise(function (resolve, reject) {
    console.log(6);
    setTimeout(resolve, ms); // (A)
  });
}

// Using delay():
let delayPromise = delay(1000).then(function () { // (B)
  console.log(7);
  console.log('1 seconds have passed!')
});

console.log('0 seconds have passed!');


function all_test(ms) {
  return new Promise(function (resolve, reject) {
    console.log(8);
    setTimeout(resolve, ms); // (A)
  });
}



Promise.all([
  delayPromise,
  async1
])
  .then(([result1, result2]) => {
    console.log(9);
    console.timeEnd('A');
    console.time('B');
    all_test(5000).then(function () { // (B)
      console.log('5 more seconds have passed!');
      console.timeEnd('B');
      console.trace('trace to here?')
    });
    console.log('successful all_test');
    console.log('result1',result1);
    console.log('result2',result2);
  })
  .catch(err => {
    console.log(10);
    // Receives first rejection among the Promises
    console.log('ERROR', err)
  });