function buscar() {
      var form = document.forms['countrycode'];
      var resultado = document.getElementById("resultado");
      var contenttype = 'application/x-www-form-urlencoded';
      var req;
      if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
      } else {
        req = new ActiveXObject("Microsoft.XMLHTTP");
      }
      req.open('POST', '../codigos-area/search2.php', true);
      req.setRequestHeader('Content-Type', contenttype);
      req.onreadystatechange =
        function() {
          if (req.readyState == 4)
            resultado.innerHTML = req.responseText;
       }
      req.send('city=' + escape(form.city.value));
    }