[Luca]

Babel в помощь

'use strict';
var main = function () {
  var _ref = _asyncToGenerator(regeneratorRuntime.mark(function _callee() {
    return regeneratorRuntime.wrap(function _callee$(_context) {
      while (1) {
        switch (_context.prev = _context.next) {
          case 0:
            console.log('begin');
            _context.next = 3;
            return asyncWork(10000);

          case 3:
            console.log('end');

          case 4:
          case 'end':
            return _context.stop();
        }
      }
    }, _callee, this);
  }));

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

function asyncWork(ms) {
  var i = 0;
  return new Promise(function (resolve) {
    var foo = function foo() {
      if (i > 99) {
        resolve();
      } else {
        i++;
        console.log(i + '% is done');
        setTimeout(foo, ms / 100);
      }