Hey Jace,

Nice work on the count feature.  I couldn't get the info to render properly though based on the above code snippet.  Kept getting parsing errors around the modified_thumb_content code, and my javascript skills aren't very good (ok, my javascript is crap, I'm a data warehouse developer).  I wasn't able to get it to work properly on my system.  

However, I was able to hack together your counting code with the original to provide a less fancy version that gives a little more info than lostndessence's original.  No progress bar, but a page x of y and completed status text.  

Here's the hacked together code if anyone's interested:

// Anonymous "self-invoking" function
(function() {
    var startingTime = new Date().getTime();
    // Load the script
    var script = document.createElement("SCRIPT");
    script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js';
    script.type = 'text/javascript';
    document.getElementsByTagName("head")[0].appendChild(script);

    // Poll for jQuery to come into existance
    var checkReady = function(callback) {
        if (window.jQuery) {
            callback(jQuery);
        } else {
            window.setTimeout(function() { checkReady(callback); }, 20);
        }
    };

    // Start polling...
    checkReady(function($) {
        //////////////////////////////////
        //Add currently reading condition to comic
        //////////////////////////////////
        $('.thumb a img').each(function(){
            raw_src = $(this).attr('src')
            page_num = '0';
            //sort comics from folders
            if (raw_src.search("folder") >= 0){
                //console.log("raw_src: "+raw_src);
            } else {
                //extract Comic ID
                thing = $(this);
                src = $(this).attr('src');                //console.log("source: "+src);
                $(this).closest('.thumb').append('<div class="numberblock"><div class="number"><span></span></div></div>');
                var comicid = src.split('/');            //console.log("Comic ID: "+comicid[2]);
                //get comic meta from server
                json_url = window.location.origin+"/user-api/bookmark?docId="+comicid[2];        //console.log("url: "+json_url);
                $.getJSON( json_url, function() {
                    console.log( "json_url success" );
                }).done(function( data ) {
                    current_this = thing;
                    if (data != null){
                        var items = [];
                        var c_id = '';
                        var c_pages = '';
                        var page_num = '';
                        $.each( data, function( key, val ) {
                            if (key == 'docId'){c_id = val;}
                            if (key == 'mark'){page_num = val;}
                        });
                        if (page_num != '0'){
                            // get total pages from server
                            content_url = window.location.origin+"/comicdetails/"+c_id;    //console.log("url: "+content_url);
                            $.get( content_url, function() {
                                //console.log( "content_url success" );
                            }).done(function( data ) {
                                details = $('<details>').append($.parseHTML(data));
                                size_div = $('#details_size', details).html();
                                c_pages = size_div.match(/\d+/)[0];

                                if (page_num >= (c_pages-1)) {
                                    progress_percent = 100;
                                    progress_string = "Completed";
                                } else {
                                    progress_percent = ((page_num/c_pages) * 100);
                                    page_int = Number(page_num)+1;
                                    progress_string = (page_int++) + " of " + c_pages;
                                }

                                    $("img[src*='"+c_id+"']").closest('.thumb').find('.number').html(progress_string);
                                    $("img[src*='"+c_id+"']").closest('.thumb').find('.numberblock').addClass("reading");

                            });
                        }
                        console.log("page_num "+page_num);
                    }
                }).fail(function(){});
            }
        console.log("triggered");
        });
    });
})();
// end Anonymous "self-invoking" function</details>

Love the reading tag, nice work!  Any updates on whether completed or a progress bar will be possible?

Thx!