ZenPhoto preloading

/*Image preloading for ZenPhoto default theme. Just add to your image.php.
Ulf Benjaminsson 2011-07-30 */
jQuery(document).ready(function($) {
    var $nextlink = $('.imgnext > a:first-child');
    var nextURL = ($nextlink) ? $nextlink.attr('href') : '';
    if(nextURL == ''){return;}
    $.get(nextURL, function(data, textStatus) {
        if(textStatus !== "success"){return;}
        if(console){
            var n = nextURL.length;
            console.log('Preloaded: '+nextURL.substring(n, n-17));
        }
        $nextlink.click(function(e) {
            e.preventDefault();
            if(history && (typeof history.pushState == 'function')){
                history.pushState({}, "", nextURL);
            }
            document.open();
            document.write(data);
            document.close();
        })
    });
});