Discovery of async/await internals

package.json

{
  "name": "test-async",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "babel": {
    "presets": [
      [
        "env",
        {
          "targets": {
            "node": "4.0"
          }
        }
      ]
    ]
  },
  "dependencies": {
    "babel-cli": "^6.26.0",
    "babel-core": "^6.26.3",
    "babel-preset-env": "^1.7.0"
  }
} 

test.es5.js

"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"); }); }; }

var foo = function () {
  var _ref = _asyncToGenerator( /*#__PURE__*/regeneratorRuntime.mark(function _callee() {
    return regeneratorRuntime.wrap(function _callee$(_context) {
      while (1) {
        switch (_context.prev = _context.next) {
          case 0:
            _context.next = 2;
            return bar();

          case 2:
            return _context.abrupt("return", _context.sent);

          case 3:
          case "end":
            return _context.stop();
        }
      }
    }, _callee, undefined);
  }));

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

var bar = function bar() {
  return new Promise(function (resolve) {
    return setTimeout(function () {
      return resolve();
    }, 100);
  });
}; 

test.js

const foo = async () => await bar();

const bar = () => new Promise(resolve => setTimeout(() => resolve(), 100));