58 lines, 1 of them comments · 488 tokens, written in 3 seconds for $0.0041

 1  let balls = [];
 2  let numBalls = 15;
 3  
 4  function setup() {
 5    createCanvas(600, 400);
 6    for (let i = 0; i < numBalls; i++) {
 7      let r = random(18, 35);
 8      let b = new Ball(
 9        random(r, width - r),
10        random(r, height - r),
11        r
12      );
13      balls.push(b);
14    }
15    noStroke();
16  }
17  
18  function draw() {
19    background(30, 30, 50);
20    for (let b of balls) {
21      b.move();
22      b.bounce();
23      b.display();
24    }
25  }
26  
27  class Ball {
28    constructor(x, y, r) {
29      this.x = x;
30      this.y = y;
31      this.r = r;
32      this.vx = random(-3, 3);
33      this.vy = random(-3, 3);
34      this.color = color(random(255), random(255), random(255));
35    }
36    move() {
37      this.x += this.vx;
38      this.y += this.vy;
39      // Change color slightly as it moves
40      this.color = color(
41        (red(this.color) + random(-2, 2)) % 255,
42        (green(this.color) + random(-2, 2)) % 255,
43        (blue(this.color) + random(-2, 2)) % 255
44      );
45    }
46    bounce() {
47      if (this.x < this.r || this.x > width - this.r) {
48        this.vx *= -1;
49      }
50      if (this.y < this.r || this.y > height - this.r) {
51        this.vy *= -1;
52      }
53    }
54    display() {
55      fill(this.color);
56      ellipse(this.x, this.y, this.r * 2);
57    }
58  }