Enhancement of interview questions (ES6 classes)

[deyantomov]

I want to update the intermediate level interview questions with a section about ES6 classes with the following questions:

1. What are JavaScript classes?
2. Class members (fields and methods) and class properties (getters and setters)
4. Explain constructor functions
5. Static members vs Instance members
6. Member visibility

[sumn2u]

I want to update the intermediate level interview questions with a section about ES6 classes with the following questions:

1. What are JavaScript classes?
2. Class members (fields and methods) and class properties (getters and setters)
4. Explain constructor functions
5. Static members vs Instance members
6. Member visibility

@deyantomov These topics are helpful. We would love to see your contributions.