[рони]

<div class="time"></div>
    <script>
var x = 24*60*60*1000; // тоесть сутки
down = document.querySelector('.time'),
end = x;

function tick(e){
    var ost = end - e;
    if(ost < 0) {end = ost = x};
    var s = Math.floor(ost/1000),
    m = Math.floor(s/60),
    h = Math.floor(m/60),
    d = Math.floor(h/24);
    s = s%60+'';
    m = m%60+'';
    h = h%24+'';
    d = d+'';
    d = d.length == 1 ? '0'+d:d;
    h = h.length == 1 ? '0'+h:h;
    m = m.length == 1 ? '0'+m:m;
    s = s.length == 1 ? '0'+s:s;

    down.innerHTML = d+' дней '+h+' часов '+m+' минут '+s+' секунд';
    requestAnimationFrame(tick)

};
 requestAnimationFrame(tick)

    </script>