const padding = 20

​

function setup() {

  createCanvas(400, 400);

  noLoop() // Looks cool also

  strokeWeight(2)

}

​

function draw() {

  background(240);

​

  for (let y = padding; y <= height - padding;) {

    const h = random(10, 150)

    for (let x = padding; x < width - padding; x += random(0, random([0, 3, 5, 10]))) {

      random(1) > 0.5 ? stroke(0) : stroke(240)

      line(x, y, x, y + h > height - padding ? height- padding : y + h )

    }

    y += h + 2

  }

}