Mandelbrot Fractal

HTML

<canvas id="fractal" width="800" height="800"></canvas>

JavaScript

var x, y, i, xt, cx, cy, zx, zy, color;
var canvas = document.getElementById("fractal"), context = canvas.getContext('2d');

for(x = 0; x < 200; x++) {
	for(y = 0; y < 200; y++) {
  	i = 0;
    cx = -2 + x / 50;
    cy = -2 + y / 50;
    zx = 0;
    zy = 0;
    
    do {
    	xt = zx * zy;
      zx = zx * zx - zy * zy + cx;
      zy = 2 * xt + cy;
      i++;
    }
    while(i < 255 && (zx * zx + zy * zy) < 4);
    
    color = i.toString(16);
    context.beginPath();
    context.rect(x * 4, y* 4, 4, 4);
    context.fillStyle = "#" + color + color + color;
    context.fill();
  }
}