<!--Impide refrescar-->
   document.onkeydown = function(){ 
    if(window.event && window.event.keyCode == 116){ 
     window.event.keyCode = 505; 
    } 
    if(window.event && window.event.keyCode == 505){ 
     return false;     
    } 
   } 

 <!--Escuchar Demos-->
function demo(URL) 
{
day = new Date();
id = day.getTime();
eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=250,height=175,left = 0,top = 0');");
}

<!--Valida Formulario Boletin-->
function Verif(theForm)
{   
	    email=theForm.email.value;
	if (email.indexOf('@',0)==-1 || email.indexOf('.',0)==-1
		|| email.indexOf(' ',0)!=-1 || email.indexOf('/',0)!=-1
		|| email.indexOf(';',0)!=-1 || email.indexOf('<',0)!=-1
		|| email.indexOf('>',0)!=-1 || email.indexOf('*',0)!=-1
		|| email.indexOf('|',0)!=-1 || email.indexOf('`',0)!=-1
		|| email.indexOf('&',0)!=-1 || email.indexOf('$',0)!=-1
		|| email.indexOf('!',0)!=-1 || email.indexOf('"',0)!=-1
		| email.indexOf('á',0)!=-1 || email.indexOf('é',0)!=-1
		| email.indexOf('í',0)!=-1 || email.indexOf('ó',0)!=-1
		| email.indexOf('ú',0)!=-1 || email.indexOf('ñ',0)!=-1
		|| email.indexOf(':',0)!=-1) 
		{
			alert("Please, Check Your E-mail Address. \nNo > / ; < > * | etc...\n Also Check: @ .");
		theForm.email.focus();      
		return (false);     
	}




	if (theForm.password.value.length < 6)
  {
    alert("Min. 6 Characters in \"Password\".");
    theForm.password.focus();
    return (false);
  }

  if (theForm.password.value.length > 10)
  {
    alert("Max. 10 Characters in \"Password\".");
    theForm.password.focus();
    return (false);
  }
		return (true);   
}

<!--Valida Formulario Buscar-->
function FrontPage_Form1_Validator(theForm)
{

  if (theForm.buscando.value == "")
  {
    alert("No Characters in \"Search\".");
    theForm.buscando.focus();
    return (false);
  }

  if (theForm.buscando.value.length < 4)
  {
    alert("Min. 4 Characters in \"Search\".");
    theForm.buscando.focus();
    return (false);
  }

  if (theForm.buscando.value.length > 15)
  {
    alert("Max. 15 Characters in \"Search\".");
    theForm.buscando.focus();
    return (false);
  }
  return (true);
}

function Validar_Tarjeta(theForm)
{
  if (theForm.tarjetaNumero.value == "" || theForm.tarjetaNumero.value == " ")
  {
    alert("El campo \"Nº Tarjeta\" está sin rellenar");
    theForm.tarjetaNumero.focus();
    return (false);
  }

  if (theForm.tarjetaNumero.value.length < 16)
  {
    alert("El campo \"Nº Tarjeta\" debe contener 16 dígitos");
    theForm.tarjetaNumero.focus();
    return (false);
	  }

  if (theForm.caducidad.value == "" || theForm.caducidad.value == " ")
  {
    alert("El campo \"Caducidad\" está sin rellenar");
    theForm.caducidad.focus();
    return (false);
  }

  if (theForm.caducidad.value.length < 4)
  {
    alert("El campo \"Caducidad\" debe contener 4 dígitos");
    theForm.caducidad.focus();
    return (false);
	  }
  return (true);
}


<!--

function acceptNum(evt){	
var nav4 = window.Event ? true : false;
// NOTE: Backspace = 8, Enter = 13, '0' = 48, '9' = 57	
var key = nav4 ? evt.which : evt.keyCode;	
return (key <= 13 || (key >= 48 && key <= 57));
}
//-->