async / await を使ったパターン

es-next-async-await-ex.js

'use strict';

import 'babel-regenerator-runtime';
// require('babel-polyfill'); // おまじない
//require('regenerator').runtime();

console.log('main: start');
main().then(function (val) {
  console.log('main: finish:', val);
});

async function main() {
  var result;
  console.log('main: started');

  // シーケンシャル処理(逐次処理)
  result = await sleep(1000, 'a1');
  console.log('main-a1: sleep: a1 =', result);
  result = await sleep(500, 'a2');
  console.log('main-a2: sleep: a2 =', result);

  // パラレル処理(並行処理)
  result = await Promise.all([sleep(200, 'b1'), sleep(100, 'b2'), sleep(300, 'b3')]);
  console.log('main-b : Promise.all([promises]): [b1, b2, b3] =', result);

  return 'return value!';
}

function sleep(msec, val) {
  return new Promise(function (resolve, reject) {
    setTimeout(resolve, msec, val);
  });
}