Can JavaScript make an app?

Answer 1

Yes. With JavaScript you can also made games. The popular Game Dev Tycoon Game was made with JavaScript.
With an JavaScript Framework you can made apps.

Answer 2

Yes! You can use MEAN. M= MongoDB E=Express.js A=Angular (you can use Angular 2 also) N= Node.js
Or use Ember.js, Angular, Angular2, React.js, React Native with Android Studio for Mob Apps...and a lot more

Answer 3

Yes it can be used to make web apps.

Answer 4

Yes. For mobile devices, you need use the cordova/phonegap Framework