get the biggest image on a page with a reasonable aspect ratio with javascript

biggest_image.js

var biggestImage = function() {
  biggest = null;
  images = document.getElementsByTagName('img');
  for (var i = 0; i < images.length; i++) {
    var image = images[i];
    var area = image.width * image.height;
    var ratio = image.width / image.height;
    if(!biggest || (area > 1 && area > (biggest.width * biggest.height) && ((ratio > 1 && ratio < 2) || (1/ratio > 1 && 1/ratio < 2))))
    {
      biggest = image;
    }
  }
  return biggest;
}