async functions without a transpiler

async-without-babel.js

var Promise = require('bluebird');

var examplePromise1 = Promise.delay(5000);
var examplePromise2 = Promise.delay(2000).return('myValue');

// the following two are equivalent:

// 1. Async function (ES7, only available with a transpiler)
var func = async function (arg1, arg2, arg3) {
  await examplePromise1;
  var value = await examplePromise2;
  return value + ' some other string ' + (arg1 + arg2 + arg3);
}

// 2. Generator function (bluebird feature)
Promise.coroutine.addYieldHandler(Promise.resolve); // This line ensures that synchronous values can be yielded
var func2 = Promise.coroutine(function* (arg1, arg2, arg3) {
  yield examplePromise1;
  var value = yield examplePromise2;
  return value + ' some other string ' + (arg1 + arg2 + arg3);
});

// ---

func(1, 2, 3).then(console.log); // prints 'myValue some other string 6' after 7 seconds
func2(1, 2, 3).then(console.log); // does the exact same thing