Variable Size Background (jQuery)

gistfile1.js

(function() {
  // Background image variable size (keeping aspect ratio fixed)
  // Based on http://jonathanstark.com/blog/2011/01/03/variable-size-background-image/
  // By Jorge Barnaby (jorge {dot} barnaby {at} gmail) - Jun 2012

  // Background image
  var imgPath = 'assets/background.jpg'; // Path of the image to be used as background
  var origW = 1920; // Original width of the image
  var origH = 1080; // Original height of the image
  var ratio = origW / origH;

  // Image jQuery object
  var bgImg = $('<img>').attr('src', imgPath).height(origH).width(origW).css({position: 'absolute', left: '0px', top: '0px', zIndex: '-1'});
  // Background wrapper jQuery object
  var bg = $('<div></div>').height(origH).width(origW).css({position: 'absolute', left: '0px', top: '0px', zIndex: '-1'});
  
  // Append elements
  bg.append(bgImg);
  $('body').append(bg);
  
  // Set the image size based on window size
  setBackgroundImageSize();

  // Prevent page scrolling on touch devices
  $('body').bind('touchmove', function(e) {
    e.preventDefault();
  });
  
  //Bind resize function to events
  $(window)
    .bind('resize', function() {
      setBackgroundImageSize();
    })
    .bind('orientationchange', function () {
      setBackgroundImageSize();
    });
    
  function setBackgroundImageSize() {
    var w = $(window).width();
    //var h = $(window).height();
    var h = Math.round(w / ratio);
    $(bg).height(h).width(w);
    $(bgImg).height(h).width(w);
  }
})();