function checkEmail (email) {
    if( email=="" ) return false;
    
    var regExpr = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,})+$/;
    return regExpr.test(email);
}

function checkContactForm() {
    if (!document.getElementById("message")) return false;
    if (!document.getElementById("email")) return false;
    
    var msgText = document.getElementById("message").value;
    var emailText = document.getElementById("email").value;
    
    if (!checkEmail(emailText) || msgText == "") {
        document.getElementById("error_div").style.display="block";
        return false;
    }

    return true;
}

function checkFreeSampleForm() {
    if (!document.getElementById("address")) return false;
    if (!document.getElementById("email")) return false;
    
    var msgText = document.getElementById("address").value;
    var emailText = document.getElementById("email").value;
    
    if (!checkEmail(emailText) || msgText == "") {
        document.getElementById("error_div").style.display="block";
        return false;
    }

    return true;
}