A jQuery plugin that changes a background images position to fixed once you've scrolled the page to the bottom of the image

bgScrollFix.js

$.fn.bgScrollFix = function() {
  var imageSrc = this.css('background-image').replace(/"/g,"").replace(/url\(|\)$/ig, "").split(',')[0];
  var image = new Image();
  image.src = imageSrc;
  $(window).scroll(function(){
    if((image.height - $(window).height()) <= $(window).scrollTop()) {
      $('body').addClass('fixed');
    } else {
      $('body').removeClass('fixed');
    }
  });
};