Can JavaScript work by itself, or does it have to have another helping language?

Answer 1

Check out what you can do with pure JS.

https://www.quora.com/What-are-some-of-the-cool-projects-that-I-can-build-using-Pure-JavaScript

Answer 2

JavaScript is evolving. with 2015 ECMAScript 6 ( classes and modules) we can do OOP in JavaScript.
There are great frameworks/libraries/platforms like Node.js(Serverside JavaScript Environment ), Angular,React,and many written on JavaScript.

More info on version: https://www.w3schools.com/js/js_versions.asp