doSomething().then(function () {
  return doSomethingElse();
});

doSomething().then(function () {
  doSomethingElse();
});

doSomething().then(doSomethingElse());

doSomething().then(doSomethingElse);

One of common concerns I faced in web/frontend development is libraries like “Angularjs, Bootstrap, JQuery… etc..” loading time, and how that affect on website performance, when you need to load several libraries to your website/page.. specially with low internet speed connections