YouTube subscriber-counter

<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>YouTube subscriber-counter</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js" type="text/javascript" charset="utf-8"></script>
<script type="text/javascript" charset="utf-8">
String.prototype.reverse=(function(){return this.split("").reverse().join("");});

var prompt_ = (function(msg,defaultText) {
    result = prompt(msg,defaultText);
    if(result==null) {
        result = defaultText;
    }
    return result;
});


var ytchannel = prompt_('YouTube-channel name:', 'CaptainSparklez');
var thousands_separator = prompt_("Thousands-separator", ' ');
var update_interval = prompt_('Update interval (ms)', 1000);
var yt_api_url = "http://gdata.youtube.com/feeds/api/users/"+ytchannel+"?v=2&alt=json";


function formatNumber(num) {
    return num.toString().reverse().match(/.{1,3}/g).join(thousands_separator).reverse();
}


$( document ).ready( function() {
    var $body = $('body');
    var $number = $('#number');
    var $name = $('#name');
    var interval = 0;

    $name.text(ytchannel + ":");

    var resize = function() {
        var bodyWidth = $body.width();
        var size = 0;
        do {
            size += 1;
            $number.css('font-size', size + 'px');
        } while($number.width() < bodyWidth-10);
        $name.css('font-size', Math.round(size/7) + 'px');
        $number.css('margin-left', '-' + Math.round($number.width()/2) + 'px');
        $number.css('margin-top', '-' + Math.round($number.height()/2) + 'px');
        $name.css('margin-top', (Math.round($number.offset().top)) + 'px');
    }

    var refreshSubcount = (function() {
        $.getJSON(yt_api_url, function(data) {
            subcount = data.entry.yt$statistics.subscriberCount;
            $number.text(formatNumber(subcount));
            resize();
        });
    });

    function toggleInterval(e) {
        event.preventDefault();
        if(interval) {
            $body.addClass('pause');
            clearInterval(interval);
            interval = 0;
        } else {
            $body.removeClass('pause');
            refreshSubcount();
            interval = setInterval(refreshSubcount, update_interval);
        }
        window.getSelection().removeAllRanges();
    }
    toggleInterval();
    $(window).resize(resize);
    $body.dblclick(toggleInterval);
});
</script>
<style type="text/css">
* {
    margin: 0px;
    padding: 0px;
    font-family: Verdana, Geneva, sans-serif;
}

body {
    background-color: black;
    color: white;
    cursor: pointer;
}

body.pause {
    color: #222;
}

#name {
    text-align: center;
    text-decoration: underline;
}

#number {
    font-weight: bold;
    top: 50%;
    left: 50%;
    position: absolute;
    margin-top: -65px;
    margin-left: 0px;
    white-space: nowrap;
}
</style>
</head>
<body class="pause">
    <div id="name"></div>
    <div id="number">Loading....</div>
</body>
</html>