<?php 
 
if($_GET){
 
$probando=$_GET['probando'];
echo $probando;
}
 
?>

<?php
echo "GET: ".$_GET["test"];
echo "POST: ".$_POST["post"];
 
echo ' 
<form method="GET">
<input type="text" name="test"> GET
<input type="submit">
</form>
 
<form method="POST">
<input type="text" name="post"> POST
<input type="submit">
</form>';
?>

<script language="javascript">
var remplaza = /\+/gi;
var url = window.location.href;
url = unescape(url);
url = url.replace(remplaza, " ");
url = url.toUpperCase();
function obtener_valor(variable)
{
 var variable_may = variable.toUpperCase();
 var variable_pos = url.indexOf(variable_may);
 if (variable_pos != -1)
 {
  var pos_separador = url.indexOf("&", variable_pos);
  if (pos_separador != -1)
  {
   return url.substring(variable_pos + variable_may.length + 1, pos_separador);
  } else  {
   return url.substring(variable_pos + variable_may.length + 1, url.length);
  }
 } else  {
 return "NO_ENCONTRADO";
 }
}
</script>
 
 
<script language="javascript">
var valor = obtener_valor("test");
document.write ("Valor: [" + valor + "]");
</script>