image_1 = new Image();
image_1.src = "_img/btn_submit_2_on.jpg";

image_2 = new Image();
image_2.src = "_img/btn_submit_2_click.gif";

function checkLogin() {
    var myLogin = document.getElementById("login");
    var myPassword = document.getElementById("password");
    var error = '';
    if (myLogin.value == '' || myLogin.value == 'user login') {
        error += "Enter your login name!\n";
    }
    if (myPassword.value == '' || myPassword.value == 'password') {
        error += "Enter your password!\n";
    }
    if (error == '') {
        return true;
    } else {
        alert (error);
        return false;
    }
}
function checkMessage() {
    var myName = document.getElementById("name");
    var myMail = document.getElementById("mail");
    var myPhone = document.getElementById("phone");
    var myMsg = document.getElementById("message");
    var error = '';
    if (myName.value == '') {
        error += "Enter your name!\n";
    }
    if (myMail.value == '') {
        error += "Enter your mail!\n";
    }
    if (myPhone.value == '') {
        error += "Enter your phone!\n";
    }
    if (myMsg.value == '') {
        error += "Enter your message!\n";
    }
    if (!checkEmail()) {
        error += "Please provide a valid email address!\n";
    }
    if (error == '') {
        return true;
    } else {
        alert (error);
        return false;
    }
}
function checkEmail() {
    var email = document.getElementById('mail');
    var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    if (!filter.test(email.value)) {
        return false;
    } else {
        return true;
    }
}