codice:
<script language="jscript">
function salva() {
var fs = new ActiveXObject("Scripting.FileSystemObject"); 
var a = fs.CreateTextFile("c:\\testfile.txt", true); 
a.WriteLine("Il testo inserito è:\r\n"+document.miomodulo.testo.value); 
a.Close();
}
</script>
<form name="miomodulo">
<input type="text" name="testo" />
<input type="button" value="salva in c:\\testfile.txt" onclick="salva()" />
</form>