async.build.js

"use strict";

var _this = this;

var timer = function (sec) {
  return new Promise(function (done) {
    setTimeout(function () {
      done(sec);
      console.log("done");
    }, sec);
  });
};

(function callee$0$0() {
  var a;
  return regeneratorRuntime.async(function callee$0$0$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        console.log("wait for 1 sec...");
        context$1$0.next = 3;
        return timer(1000);

      case 3:
        console.log("wait for 1.5 sec...");
        context$1$0.next = 6;
        return Promise.all([timer(1500), timer(1200)]);

      case 6:
        a = context$1$0.sent;

        console.log("a is", a);

      case 8:
      case "end":
        return context$1$0.stop();
    }
  }, null, _this);
})();

async.js

let timer = (sec) => new Promise((done) => {
  setTimeout(() => {
    done(sec);
    console.log('done');
  }, sec);
});

(async () => {
  console.log('wait for 1 sec...');
  await timer(1000);
  console.log('wait for 1.5 sec...');
  let a = (await* [timer(1500), timer(1200)]);
  console.log("a is", a)
})();