var ComunasCacheArray = new Array();

function obtenerComunasPorRegion(obj, comunaObj) {
  if(obj.selectedIndex > 0) {
    region = obj.options[obj.selectedIndex].value;
    cc1 = ComunasCacheArray[region];
    if(!cc1) {
      myXml = getXmlObj();
      myXml.open('POST', '/sr.php', true);
      myXml.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
      myXml.send('op=obtenerComunasPorRegion&region=' + encodeURI(region) + '&comunaObj=' + encodeURI(comunaObj));
      myXml.onreadystatechange = function() {
        if(myXml.readyState == 4)
          eval(myXml.responseText);
      }
    } else
      poblarComunas(region, comunaObj);
  } else
    resetSelectObj(comunaObj);
}

function poblarComunas(region, comunaObj) {
  resetSelectObj(comunaObj);
  for(i = 0; i < ComunasCacheArray[region].length; i++) {
    optval = ComunasCacheArray[region][i].split('|');
    mySelect.options[i + 1] = new Option(optval[1], optval[0]);
  }
  mySelect.options[0].selected = true;
}

function resetSelectObj(comunaObj) {
  mySelect = document.getElementById(comunaObj);
  for(i = mySelect.options.length; i >= 0; i--)
    mySelect.options[i] = null;
  mySelect.options.length = 0;
  mySelect.options[0] = new Option('Seleccione una opci\u00f3n...', '0');
}