preload.jquery.js

/*
* Preload images that aren't visible on page load
* Works for images and background images
*
* $("#img1, #div2").preload()
*/

$.fn.preload = function() {
  this.each( function() {
    src = $(this).attr("src");
    if (!src) {
      bi = $(this).css("background-image");
      var match;
      if (match = bi.match(/url\(['"]?([^'"\)]+)['"]?\)/)) {
        src = match[1];
      }
    }
    if (src) {
      $("<img/>")[0].src = src;
    }
  })
}