[рони]

<script language="JavaScript" type="text/javascript">
function random(min,max,l)
{var arr = [],m = [],n = 0;
  if (max - min < l-1) return;
  for (var i=0; i<=(max-min); i++)m[i] = i + min;
  for (var i=0; i<l; i++) {n = Math.floor(Math.random()*(m.length)); arr[i]=m.splice(n,1);}; 
  return arr
}
var arr = random(0,8,4);
alert(arr);
</script>