Draw text on favicon

favtext.js

(function () {
var canvas = document.createElement('canvas'),
    ctx,
    img = document.createElement('img'),
    link = document.getElementById('favicon').cloneNode(true),
    day = (new Date).getDate() + '';

if (canvas.getContext) {
  canvas.height = canvas.width = 16; // set the size
  ctx = canvas.getContext('2d');
  img.onload = function () { // once the image has loaded
    ctx.drawImage(this, 0, 0);
    ctx.font = 'bold 10px "helvetica", sans-serif';
    ctx.fillStyle = '#F0EEDD';
    if (day.length == 1) day = '0' + day;
    ctx.fillText(day, 2, 12);
    link.href = canvas.toDataURL('image/png');
    document.body.appendChild(link);
  };
  img.src = 'ical-icon.png';
}

})();