function checkUserInput() {
    var username = document.getElementById("txtUserName");
    var userEmail = document.getElementById("txtUserEmail");
    var userNationality = document.getElementById("txtUserNationality");
    if (username.value == "") {
        alert("Please input your full name.");
        username.focus();
        return false;
    }
    if (userEmail.value == "") {
        alert("Please input your E-mail address.");
        userEmail.focus();
        return false;
    }
    //var reg=\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*;
    var reg = /(\S)+[@]{1}(\S)+[.]{1}(\w)+/;
    if (!reg.test(userEmail.value)) {
        alert("You have input a wrong E-mail address, please try again!");
        userEmail.focus();
        return false;
    }
    if (userNationality.value == "") {
        alert("Please input your nationality");
        userNationality.focus();
        return false;
    }
    document.getElementById("divWait").style.display = "block";
    document.getElementById("btnSubmit").style.display = "none";
}

function ETCheckUserInput() {
    var username = document.getElementById("txtUserFullName");
    var userEmail = document.getElementById("txtUserEmail");
    if (username.value == "") {
        alert("Please input your full name.");
        username.focus();
        return false;
    }
    if (userEmail.value == "") {
        alert("Please input your E-mail address.");
        userEmail.focus();
        return false;
    }
    //var reg=\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*;
    var reg = /(\S)+[@]{1}(\S)+[.]{1}(\w)+/;
    if (!reg.test(userEmail.value)) {
        alert("You have input a wrong E-mail address, please try again!");
        userEmail.focus();
        return false;
    }
    document.getElementById("senderEmail").style.display = "none";
    document.getElementById("divWait").style.display = "block";
}

function YTCheckUserInput() {
    var username = document.getElementById("txtUserName");
    var userEmail = document.getElementById("txtUserEmail");
    var userConfirmEmail = document.getElementById("txtUserConfirmEmail");
    var userNationality = document.getElementById("txtUserNationality");

    if (username.value == "") {
        alert("Please input your full name.");
        username.focus();
        return false;
    }
    if (userEmail.value == "") {
        alert("Please input your E-mail address.");
        userEmail.focus();
        return false;
    }
    //var reg=\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*;
    var reg = /(\S)+[@]{1}(\S)+[.]{1}(\w)+/;
    if (!reg.test(userEmail.value)) {
        alert("You have input a wrong E-mail address, please try again!");
        userEmail.focus();
        return false;
    }
    if (userConfirmEmail.value == "") {
        alert("Please confirm your E-mail address.");
        userConfirmEmail.focus();
        return false;
    }
    //var reg=\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*;
    var reg = /(\S)+[@]{1}(\S)+[.]{1}(\w)+/;
    if (!reg.test(userConfirmEmail.value)) {
        alert("You have input a wrong E-mail address, please try again!");
        userConfirmEmail.focus();
        return false;
    }

    if (userConfirmEmail.value != userEmail.value) {
        alert("You have input a different E-mail.");
        userConfirmEmail.focus();
        return false;
    }

    if (userNationality.value == "") {
        alert("Please input your nationality.");
        userNationality.focus();
        return false;
    }

    document.getElementById("emailSender").style.display = "none";
    document.getElementById("divWait").style.display = "block";
}

function HTCheckUserInput() {
    var userFirstName = document.getElementById("txtUserFirstName");
    var userLastName = document.getElementById("txtUserLastName");
    var userEmail = document.getElementById("txtUserEmail");
    if (userFirstName.value == "") {
        alert("Please input your first name.");
        userFirstName.focus();
        return false;
    }
    if (userLastName.value == "") {
        alert("Please input your last name.");
        userLastName.focus();
        return false;
    }
    if (userEmail.value == "") {
        alert("Please input your E-mail address.");
        userEmail.focus();
        return false;
    }
    var reg = /(\S)+[@]{1}(\S)+[.]{1}(\w)+/;
    if (!reg.test(userEmail.value)) {
        alert("You have input a wrong E-mail address, please try again!");
        userEmail.focus();
        return false;
    }
}