I'm creating a HTML, CSS & JavaScript virtual calculator.

It works like a calculator in real life.
You touch buttons, what you want to calculate etc etc.

It's already working perfect for +,-,*, & /.

Now I only want to know how to create a function so people can calculate percentages, square roots, and exponents.

For example: Math.pow (X, Y)

How do I make an option so people can chose X and Y whatever they want with my buttons?

I'm almost ready only need those three.

(Remember: It works like a real calculator ).
(Click button for basenumber > click exponent button > choose exponent with button > enter)

Thanks for reading,