Simple jquery countdown script

countdown.js

<script type="text/javascript">
    //assuming you have a div with a countdown id: <div id="countdown"></div>
    var startNumber = 5;
    var size = 150;
    var intervalTimer, newSize;

    $(function () {
        //set defaults
        $('#countdown').text(startNumber);             //set start number
        $('#countdown').css('font-size', size + 'px'); //set default font size
        $('#countdown').css('height', size + 'px');    //set div height to prevent it from resizing with shrinking text
        $('#countdown').css('text-align', 'center');   //keep the text centered withint the div so text fades out accordingly
        newSize = size;

        //begin countdown
        Countdown();
    });

    function Countdown() {
        clearInterval(intervalTimer);                  //clear timer
        newSize = size;                                //reset size to shrink text
        $('#countdown').css('font-size', size + 'px'); //set font size back to default      

        if (startNumber > 0) {
            intervalTimer = setInterval(function () { shrinkText() }, 100); //begin shrink timer

            $('#countdown').fadeOut(1000, function () {
                startNumber = startNumber - 1;
                $('#countdown').text(startNumber);
                $('#countdown').show();
                Countdown();
            });
        }
    }

    function shrinkText() {
        newSize = newSize - 15;
        $('#countdown').css('font-size', newSize + 'px');
    }
</script>