// Common code for from/to dates
var _t = null;
function vetoSubmit() {
  if (_t) {
    clearTimeout(_t);
    _t = null;
  }
}
function delayedSubmit( form ) {
  vetoSubmit();
  _t = setTimeout(function () { form.submit(); }, 1000);
}
function updatePeriod( form, from, to ) {
  var yfr = Number(form.elements[from + "_year"].value);
  var mfr = Number(form.elements[from + "_mon"].value);
  var dfr = Number(form.elements[from + "_day"].value);
  var yto = Number(form.elements[to + "_year"].value);
  var mto = Number(form.elements[to + "_mon"].value);
  var dto = Number(form.elements[to + "_day"].value);
  if (dfr && mfr && yfr && dto && mto && yto) {
    var afr = [ yfr, mfr, dfr ];
    var ato = [ yto, mto, dto ];
    var tfrom = Date.parse(afr.join("/"));
    var tto = Date.parse(ato.join("/"));
    if (tfrom < tto) {
      delayedSubmit(form);
    }
  }
}