// Global variables:
let circleX = 100;
let r, g, b;
let circleSize;

function setup() {
  createCanvas(400, 300);
}

// Draw is a forever loop (until stop run) of whatever is contained here.
// Default 60 frames per second:
function draw() {
  r = random(0,255);
  g = random(0,255);
  b = random(0,255);  
  circleSize = random(0,100);  
  background(r,g,b);
  noStroke();
  fill(255);
  circle(circleX, 150, circleSize);
  circleX = circleX + 1;
  //circleX = random(0,400)
}

function mousePressed(){
  // Reset circleX back to 0
  circleX = 0;
}