JavaScript Kodu

var canvas = document.querySelector('canvas');
var c = canvas.getContext('2d');
	var posX = 545*Math.random(),
	      posY = 350*Math.random();

setInterval(function(){
	c.fillStyle= "#000";
	c.fillRect(0,0,545,350);
	
	c.fillStyle =  "white";
	c.beginPath();
	fillStyle="white";
	c.rect(posX,posY,20,20);
	c.fill();
	posX += 1;
}, 50);