Comparing Babel + Uglify with Babel + Babili (with pretty-printing, September 2016)

1. Original Source .js

async function getTemperatureForecastAsync() {
  let response = await fetch('/forecast.json');
  let result = await response.json();
  return result.temperature;
}

2. Babel (ES2015, ES2016, ES2017) + Uglify .js

var getTemperatureForecastAsync = function () {
  var e = _asyncToGenerator(regeneratorRuntime.mark(function n() {
    var e, a;return regeneratorRuntime.wrap(function (n) {
      for (;;) switch (n.prev = n.next) {case 0:
          return n.next = 2, fetch("/forecast.json");case 2:
          return e = n.sent, n.next = 5, e.json();case 5:
          return a = n.sent, n.abrupt("return", a.temperature);case 7:case "end":
          return n.stop();}
    }, n, this);
  }));return function () {
    return e.apply(this, arguments);
  };
}();

3. Babel (ES2017, Babili) .js

let getTemperatureForecastAsync = (() => {
  var ref = _asyncToGenerator(function* () {
    let a = yield fetch('/forecast.json'),
        b = yield a.json();return b.temperature;
  });return function getTemperatureForecastAsync() {
    return ref.apply(this, arguments);
  };
})();