sequential image preloader

preloader.js

function preload(imageArray, imageCache, index) {
  Array.isArray = typeof Array.isArray == 'function' ? Array.isArray : function(a){return typeof a != 'undefined' && a.constructor == Array}
  index = index || 0;
  if (imageArray && imageArray.length > index) {
    var img = new Image ();
    var preloadFn = preload.bind(this, imageArray, imageCache, index + 1);
    img.onload = preloadFn;
    img.onerror = preloadFn;
    img.src = imageArray[index];
    if(Array.isArray(imageCache)) {
      imageCache.push(img);
    }
  }
}

// Based on http://www.photo-mark.com/notes/image-preloading/