I'm starting at web development and trying to create my first web app, a calculator, but I bumped into a bit of a problem.

I wanted an app where the user wrote the operator of the operation that needs to be performed and then the program would check this operator and run the specified equation. I know how to perform this in Python but I cannot use the same approach in JS in an HTML file.

In Python I would do something like this:

a = 4
b = 4
operator = '+'

if operator == '+':
    print(a+b)
if operator == '-':
    print(a-b)