var kurz = 30.1260;
var maxCelychCisel = 10;
var maxDesatinnychCiselSkk = 2;
var maxDesatinnychCiselEur = 4;

function ibaCisla(text, max) {
  var cnt = text.length;
  var ret = '';
  var nemamBodku = true;
  var predBodkou = 0;
  var zaBodkou = 0;
  for (i=0;i<cnt;i++) {
    var znak = text.substring(i,i+1);
    if (znak == ',') {znak = '.';}
    if (znak >= '0' && znak <= '9') {

      if (nemamBodku) {
        if (predBodkou<maxCelychCisel) {
          ret = ret + znak;
          predBodkou++;
        }
            } else {
        if (zaBodkou<max) {
          ret = ret + znak;
          zaBodkou++;
        }
      }
    }
    if (znak == '.' && nemamBodku) {
      nemamBodku = false;
      ret = ret + znak;
    }
  }
  if (ret=='.') {ret = '';}
  return ret;
}

function writeCurr(skk, eur, event) {
  if ((event.keyCode>34 && event.keyCode<41)) {return;}
  if (skk == null) {
    eur = ibaCisla(eur,maxDesatinnychCiselEur);
    skk = (eur*kurz).toFixed(2)*1;
    if (skk == 0) {skk = '';}
  } else {
    skk = ibaCisla(skk,maxDesatinnychCiselSkk);
    eur = (skk/kurz).toFixed(maxDesatinnychCiselEur)*1;
    if (eur == 0) {eur = '';}
  }
  if (document.getElementById('inputSkk').value!=skk) {document.getElementById('inputSkk').value = skk;}
  if (document.getElementById('inputEur').value!=eur) {document.getElementById('inputEur').value = eur;}
}