Button Code For JS

Yeah sure! Basically a button needs a few things:
1. a shape you have to click

2. code to react if you click it

First, you can draw a rectangle:

rect(200, 200, 100, 50);

Then use an if statement that detects if the mouse is pressed when hovering over the button:

if(mouseX > 150 && mouseX < 250 && mouseY > 175 && mouseY < 225 && mouseIsPressed) {

// write what you want to happen

}