function brojke(myfield, e) {
var key;
var keychar;

if (window.event) {
   key = window.event.keyCode;
   }
else if (e) {
   key = e.which;
   }
else {
   return true;
   }
keychar = String.fromCharCode(key);

if ((("0123456789").indexOf(keychar) > -1)||(key==0))
   return true;
else
   return false;
}