function checkWholeForm(form1) {
    var leeg = "";
    leeg += checkVoornaam(form1.voornaam.value);
    leeg += checkAchternaam(form1.achternaam.value);
    leeg += checkEmail(form1.email.value);

    if (leeg != "") {
       alert(leeg);
       return false;
    }
return true;
}


// voornaam 

function checkVoornaam (strng) {
var error = "";
if (strng == "") {
   error = "No firstname entered.\n";
}


    
    
return error;
}       


//achternaam 

function checkAchternaam (strng) {
var error = "";
if (strng == "") {
   error = "No lastname entered.\n";
}


    
    
return error;
}       

// Email

function checkEmail (strng) {
var error="";
if (strng == "") {
   error = "No email address entered.\n";
}

    var emailFilter=/^.+@.+\..{2,4}$/;
    if (!(emailFilter.test(strng))) { 
       error = "Please fill out a VALID email address.\n";
    }
    else {

       var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/
         if (strng.match(illegalChars)) {
          error = "The email address contains invalid characters.\n";
       }
    }
return error;    
}