ES6+ in Cloud Functions for Firebase - preset-env to minimally compile async-await

CF4F-ES6-2|function05.js

// Babel output - with Babel REPL settings:
// * prettify
// * preset-env Node v6.9

"use strict";

function _asyncToGenerator(fn) {
  return function() {
    var gen = fn.apply(this, arguments);
    return new Promise(function(resolve, reject) {
      function step(key, arg) {
        try {
          var info = gen[key](arg);
          var value = info.value;
        } catch (error) {
          reject(error);
          return;
        }
        if (info.done) {
          resolve(value);
        } else {
          return Promise.resolve(value).then(
            function(value) {
              step("next", value);
            },
            function(err) {
              step("throw", err);
            }
          );
        }
      }
      return step("next");
    });
  };
}

const functions = require("firebase-functions");

// returns a string after 5 seconds
const message = () => {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve(`from Babelified Cloud Functions!`);
    }, 5000);
  });
};

module.exports.helloWorld = functions.https.onRequest(
  (() => {
    var _ref = _asyncToGenerator(function*(req, res) {
      let world = yield message();
      res.status(200).send(`Hello ${world}`);
    });

    return function(_x, _x2) {
      return _ref.apply(this, arguments);
    };
  })()
);