How do you make the keys work?

Question

I am currently working on a game, and I am struggling on how to make a physics engine. I need to know how to make things happen when keys are pressed. I made a test code so that if i press the up key, it prints five, but it keeps reporting an error. Help?

Answer 1

First of all what language are you use?

Answer 2

I'm using web (HTML/CSS/JS)

Answer 3

Can you paste the code?

Answer 4

https://code.sololearn.com/WheWY5uWy4d9/#html

Answer 5

There is anything called key.