function validEmail(email) {
    if (email=="" || email== null) {
        return false;
    } else {
        var emailReg = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,6}|[0-9]{1,3})(\]?)$/; // valid
        if (!emailReg.test(email)) { // if syntax is valid
            return false;
        }
        return true;
    }
}

function chkReg(sheet) {
    if (document.sheet.nev.value=="") {
        alert(errorNoName);
        document.sheet.nev.focus();
        return false;

    } else if (document.sheet.ajnev.value=="") {
        alert(errorNoOffName);
        document.sheet.ajnev.focus();
        return false;
    
    } else if (document.sheet.email.value=="") {
        alert(errorNoEmail);
        document.sheet.email.focus();
        return false; 
        
    } if (!validEmail(sheet.email.value)) {
        alert(errorNoValidEmail);
        sheet.email.focus();
        return false;

    }
    return true;
}



function chkOffer(sheet) {
    if (document.sheet.felado_input.value=="") {
        alert(errorNoName);
        document.sheet.felado_input.focus();
        return false;
    
    } else if (document.sheet.felado_email_input.value=="") {
        alert(errorNoEmail);
        document.sheet.felado_email_input.focus();
        return false; 
        
    } else if (document.sheet.targy_input.value=="") {
        alert(errorNoSubject);
        document.sheet.targy_input.focus();
        return false; 
        
    } else if (document.sheet.cimzett_input.value=="") {
        alert(errorNoName);
        document.sheet.cimzett_input.focus();
        return false;        
        
    } else if (document.sheet.cimzett_email_input.value=="") {
        alert(errorNoEmail);
        document.sheet.cimzett_email_input.focus();
        return false;
    
    } if (!validEmail(sheet.cimzett_email_input.value)) {
        alert(errorNoValidEmail);
        sheet.cimzett_email_input.focus();
        return false;        
        
    }
    return true;
}