I am trying to read the length of a textbox from my register form. I have tried using document.getElementById() and textbox.value.length. Is there something very simple I'm am missing. I alert the result to the screen to show the textbox length. Thanks in advance.

Here is my last attempt:

function Register(){

    Alert(RegisterForm.txt_Password.value.length);

}

TextBox structure:

<form id=RegisterForm name=RegisterForm method=POST action=RegisterInsert.php onsubmit=return Register(RegisterForm)>

                    <table border=0 align=center width=100%>

                        <tr>

                            <td width=15%>Email Address:</td>

                            <td width=85%><input type=text name=txt_Email id=txt_Email/> </td>

                        </tr>

                        <tr>

                            <td width=15%>Username:</td>

                            <td width=85%><input type=text autocomplete=off name=user_name id=user_id class=user_name >

                        <span class=check  ></span></td>

                        </tr>

                        <tr>

                            <td width=15%>Password:</td>

                            <td width=85%><input type=password name=txt_Password id=txt_Password /></td>

                        </tr>

                        <tr>

                            <td>&nbsp;</td>

                            <td>&nbsp;</td>

                        </tr>

                        <tr>

                            <td>&nbsp;</td>

                            <td><input type=submit name=btn_Register id=btn_Register value=Register></td>

                        </tr>

                        <tr>

                    </table>

                    <p>&nbsp;</p>

                </form>

I use the submit button to call the Register function.