Stuck on number and letter randomization javascript

Question

So I'm stuck on this script and am having trouble figuring out how to finish it. I need it to change the new_string to be the old string after its finished its animation and then with setInterval after 1 or 2 min run the same animation from the new old string to a new string that I will grab from a JSON. Here is the script:

$(document).ready(function () {
    var old_string = "first word";
    var new_string = "second word";

    while (old_string.length < new_string.length) {
        old_string += " ";
    }
    while (new_string.length < old_string.length) {
        new_string += " ";
    }

    for (i = 0; i < 18; i++) {
        var cell_id = create_cell();
        cycle_characters(old_string.charCodeAt(i), new_string.charCodeAt(i), cell_id);
    }
});

var create_cell = function() {
    var $rack = $("#rack");
    var cell_id = "cell_" + $("#rack .cell").size() + 1;
    $rack.append($("<span class='cell first_run'>").attr("id", cell_id));
    return cell_id;
}

var cycle_characters = function (old, newer, cell_id) {
    // 32 = space; 126 = tilde
    // low-range ASCII only
    var lower_limit = 32;
    var upper_limit = 126;

    var old = parseInt(old);
    var newer = parseInt(newer);

    if (old > upper_limit || old < lower_limit) {
        old = lower_limit;
    }
    if (newer > upper_limit || newer < lower_limit) {
        newer = lower_limit;
    }

    if ("string" != typeof cell_id) {
        cell_id = $(cell_id).attr("id");
    }

    var $cell = $("#" + cell_id);

    $cell.text(String.fromCharCode(old));
    if (newer != old) {
        var call = "cycle_characters(" + (old + 1) + ", " + newer + ", " + cell_id + ")";
        if ($cell.hasClass("first_run")) {
          $cell.removeClass("first_run");
          setTimeout(call, 1000);
        } else {
          setTimeout(call, 20);
        }
    }

}

Here is also a JsFiddle

Answer 1

Here is an updated example that may be doing what you want:

http://jsfiddle.net/ktEJy/2/

Note, the setNewWord function would obviously need to pull the next word from some other source besides a random word from an array like I am doing.

And for posterity, here is the code:

$(document).ready(function () {
    var old_string = "First Word";
    var new_string = "Second Word";

    function doTheDo() {
        $('#rack').html("");
        while (old_string.length < new_string.length) {
            old_string += " ";
        }
        while (new_string.length < old_string.length) {
            new_string += " ";
        }

        for (i = 0; i < new_string.length; i++) {
            var cell_id = create_cell();
            cycle_characters(old_string.charCodeAt(i), new_string.charCodeAt(i), cell_id);
        }
    }

    function setNewWord() {
        // grab the word from some json
        words = ['Abracadabra', 'Foo bar baz splat', 'Bingo Dingo Ringo']
        new_string = words[Math.floor(Math.random() * words.length)]
        doTheDo();
    }

    function create_cell() {
        var $rack = $("#rack");
        var cell_id = "cell_" + $("#rack .cell").size() + 1;
        $rack.append($("<span class='cell first_run'>").attr("id", cell_id));
        return cell_id;
    }

    function cycle_characters(old, newer, cell_id) {
        // 32 = space; 126 = tilde
        // low-range ASCII only
        var lower_limit = 32;
        var upper_limit = 126;

        var old = parseInt(old);
        var newer = parseInt(newer);

        if (old > upper_limit || old < lower_limit) {
            old = lower_limit;
        }
        if (newer > upper_limit || newer < lower_limit) {
            newer = lower_limit;
        }

        if ("string" != typeof cell_id) {
            cell_id = $(cell_id).attr("id");
        }

        var $cell = $("#" + cell_id);

        $cell.text(String.fromCharCode(old));

        var current = '';
        $('.cell').each(function (el, i) {
            current += $(i).text(); //console.info(i);
        });

        if (current != new_string && newer != old) {
            if ($cell.hasClass("first_run")) {
                $cell.removeClass("first_run");
                setTimeout(function() {cycle_characters(old+1, newer, cell_id);}, 1000);
            } else {
                setTimeout(function() {cycle_characters(old+1, newer, cell_id);}, 20);
            }
        } else if (current == new_string) {
            old_string = new_string;
            setTimeout(function() { setNewWord();}, 3000);
        } 
    }
    doTheDo();
});