Hi

I need to use some java script validation in one of my form. Below is the form coding. I am using surface controller in MVC. 

So once i click on submit button (Customer Checkout), it will check "First Name" is entered or not. If not entered then it should no submit the form.

If there is a simple webform then i can do this easily but don't know how to do it with BeginUmbracoForm. Please help me here ?

@using (Html.BeginUmbracoForm("CheckOutCustomerOverview", "CustomerSurface", FormMethod.Post))
    {
        @*<script type="text/javascript" language="javascript">
            function validateForm(formElement)
            {
                if(formElement.billingFirstnames.Length <= 0)
                {
                    alert('Please enter First Name');
                    return false;
                }
            }
        </script>*@
        <table class="formTable">

            <tr>
                <td class="fieldLabel">
                    First Name(s):
                </td>
                <td class="fieldData">
                    <input name="billingFirstnames" id="billingFirstnames" type="text" maxlength="20" value=""
                           style="width: 200px;">
                </td>
            </tr>
            <tr>
                <td>
                    <input type="submit" value="Customer Checkout" onclick="return validateForm(this.form)" />
                </td>
            </tr>
        </table>
    }