let w = 30;

let h = 30; 

​

function setup() {

  createCanvas(800, 800);

    frameRate(10); 

    rectMode (CENTER); 

}

function draw() {

 background(19,19,19);

    for (let y = h; y < height ; y = y + height/num) {

        for (let x = w; x <width; x = x + width/num) {

            fill(255,255,102,random(150));

            rect(x, y, w, h);

}

    }}