[рони]

VTrial,

<span id="timer" long="59">60</span>
<script>
var t = setInterval (function ()
   {
   function f (x) {return (x / 100).toFixed (2).substr (2)}
   var o = document.getElementById ('timer'), s = o.innerHTML;
   s--;
   if (s < 0) s = o.getAttribute ('long');
   o.innerHTML = f(s);
   }, 1000);
</script>