p5.js

function setup() {
  createCanvas(650, 400);
  frameRate(8); // slows down the animation to reduce eye strain
}


function draw() {
  background(0);
  for (let x = 0; x <= width; x+= 50) { 
    for (y = 0; y <= height; y+=50) {
      fill(random(255));
      ellipse(x, y, 25, 25);
    }
  }
}

let dot = {
  x: 100,
  y: 50
}

let col = {
  r: 237,
  g: 34,
  b: 93
} 

function setup() {
  createCanvas(650, 400);
  background(250)
}

function draw() {
  noStroke();
  dot.x = random(0, width);
  dot.y = random(0, height)
  fill(col.r, col.g, col.b, 20);
  ellipse(dot.x, dot.y, 24, 24);
}

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

function draw() {
  background(0, 0, 50);

  fill(200, 120, 100);
  noStroke();
  rect(20, 25, 200, 200);
 
  stroke(255, 255, 255, 200);
  strokeWeight(5)
  line(0, 0, 360, 400)
}