맨 위로(Top) 버튼

<div id="<?=$uid=uniqid()?>">
    <img src="https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRyjSgmd0Hx9rY7AsO7LFDsU0w9RFELuxrh6DBExerWVTMDzt2NUw">
</div>

<script>
$(function() {
    var $uid = $('#<?=$uid?>');
   
    $uid.css({
        position:'fixed',
        right:'50px',
        bottom:'50px',
        zIndex:'999999'
    }).hide().find('>img').css({
        cursor:'pointer'
    }).click(function() {
        scrollTo(0, 0);
    });
   
    $(window).scroll(function() {
        var y = $(window).scrollTop();
        if (y > 300 && $uid.is(':hidden'))
            $uid.fadeIn('slow');
        else if (y < 300 && $uid.is(':visible'))
            $uid.fadeOut('slow');
    });
});
</script>