Does javascript support data encapsulation, polymorphism as other objetct oriented programming language

Answer 1

Yes, support something like oop. Does not have classes with methods, but you can simulate it by functions.

Answer 2

It depends on the version. In versions of Ecmascript (padrão JavaScript) below 6 you can simulate OOP with objects, functions and the prototype pattern.

In Ecmascript 6 we have new features that support OOP, mainly classes.

Many browsers don't support Ecmascript 6 yet, and that's why people continue using legacy code. But you can use Babel for translating this new version of JavaScript code to legacy code, in your projects.

Read more:

Babel:
https://babeljs.io

Classes (Ecmascript 6):
http://es6-features.org/#ClassDefinition