setup.js

let size = 500;

function setup() {
   if (windowWidth < size) {
      size = windowWidth; // p5.js property containing window width
   }
   createCanvas(size, size); // Creates a new canvas of given size
   background(25); // adds color to canvas background
   angleMode(DEGREES); // sets p5.js anglemode to degrees
   noLoop(); // stop the draw function from executing continuously
}