How do I output a value to a JS file?

Hi, I've been using Unity for a while but I am completely new to the WebGL side of things. I want to start off simple. I want to make a scene with a cube, when the cube is clicked it adds a value of 1 to an int, what's the best way of going with this? Could some one show me a script for me to study or point me in a direction? Would it write to a JS script on the server, what is required? Thanks for your time!