window.onload=function(){
if(!document.getElementById || !document.createElement) return;
document.forms[0].onsubmit=function(){
    if(Validate())
       document.forms[0].submit(addguestbook.php);
    else{
        alert("Attenzione: i campi evidenziati non sono validi");
        return(false);
        }
    }
}
 
function Validate(){
var labels=document.getElementsByTagName("label");
var validationOK=true;
for(var i=0;i<labels.length;i++){
    var lab=labels[i];
    if(lab.className=="req2") lab.className="req";
    if(lab.className=="req"){


        var inp=lab.getElementsByTagName("input");

        if(inp.length>0 && (inp[0].id=="numero")){ //num non valido
        if(isNaN(inp[0].value)){
            lab.className="req2";
            validationOK=false;
           }
        }

        if(inp.length>0 && inp[0].value==""){  //input vuoto
            lab.className="req2";
            validationOK=false;
            }
        if(inp.length>0 && inp[0].id=="email"){ //email non valida
        if(!isEmail(inp[0].value)){
            lab.className="req2";
            validationOK=false;
            }
        }

      }
    }
return(validationOK);
}



function isEmail(str){
var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
return (!r1.test(str) && r2.test(str));
}