<canvas id="canvas"></canvas>

const canvas = document.querySelector('#canvas')
const ctx = canvas.getContext('2d')

canvas.width = window.innerWidth
canvas.height = window.innerHeight
ctx.fillStyle = 'black'


let point = {x: canvas.width/2, 
             y: canvas.height/2}

function render(){
  point.x += (Math.random()-.5)*5
  point.y += (Math.random() -.5)*5
  ctx.rect( point.x, point.y, 5, 5)
  ctx.fill()
 
  window.requestAnimationFrame(render);
}

render()