我的注册表格不断刷新页面

Question

在我的本地服务器上它工作得很好但是一旦我把它带到现场它开始只引用页面而不是调用验证。

这是我的jquery：

<script>
    $("form#registerform").submit(
        function (e) {
            e.preventDefault();
            function validateForm() {
                var RegisterUsername = document.forms["contactForm"]["RegisterUsername"].value;
                var FirstName = document.forms["contactForm"]["FirstName"].value;
                var LastName = document.forms["contactForm"]["LastName"].value;
                var Email = document.forms["contactForm"]["Email"].value;
                var RegisterPassword = document.forms["contactForm"]["RegisterPassword"].value;


                if (RegisterUsername == null || RegisterUsername == "") {
                    $(".error-messages").text("Username required").fadeIn(300).delay(1000).fadeOut(300);
                    return false;
                }
                else if (FirstName == null || FirstName == "") {
                    $(".error-messages").text("First name required").fadeIn(300).delay(1000).fadeOut(300);
                    return false;
                } else if (LastName == null || LastName == "") {
                    $(".error-messages").text("Last name required").fadeIn(300).delay(1000).fadeOut(300);
                    return false;
                }
                else if (Email == null || Email == "") {
                    $(".error-messages").text("Email required").fadeIn(300).delay(1000).fadeOut(300);
                    return false;
                }
                else if (RegisterPassword == null || RegisterPassword == "") {
                    $(".error-messages").text("Password required").fadeIn(300).delay(1000).fadeOut(300);
                    return false;
                }
            }

        }
</script>

这是我的HTML：

<form id="registerform" name="contactForm" action="" onsubmit="return validateForm()" method="post">

    <div class="pl-land-input">
        <input class="email text-input" id="RegisterUsername" pattern=".{3,}" title="3 characters minimum" name="RegisterUsername" placeholder="Username" type="text" value="">
    </div>
    <div class="pl-land-input">
        <input class="email text-input" id="FirstName" name="FirstName" placeholder="First Name" type="text" value="">
    </div>
    <div class="pl-land-input">
        <input class="email text-input" id="LastName" name="LastName" placeholder="Last Name" type="text" value="">
    </div>

    <div class="pl-land-input">
        <input class="email text-input" type="email" placeholder="Email"  name="Email" id="Email">
    </div>

    <div class="pl-land-input">
        <input class="email text-input" id="RegisterPassword" name="RegisterPassword" placeholder="Password" type="password">
    </div>

    <button type="submit" value="Submit" class="signup-plland">Sign up</button>

</form>

我一直试图绕过它并继续定制它但我无法弄清楚问题在控制台中调用Jquery库没有问题。

我希望我尽快解决这个问题。