Beispiel aus dem Kapitel Processing in JavaScript.
var x = 10;
var s = 2;
function setup() {
createCanvas(200, 200);
}
function draw() {
background(0);
ellipse(x, height/2, 20, 20);
x = x + s;
if (x > width-10 || x < 10) {
s = -s;
}
}