For check boxes and radio buttons use code like this:

if (document.getElementById("checkbox_or_radio_button_id_here").getChecked() == true)
{
    // yes it was checked
}

For dropdown:

if (document.getElementById("dropdown_id_here").getValue() !=   )
{
    // yes dropdown was not empty
}

I personally don t use serialize in facebook validation, i just use simple code as above.

Thanks, hope that helps.

I am using simple code too. I can t figure out why when I submit with an error, I get the dialogue and the form goes ahead and submits anyway.

//....
var txt = Enter Zipcode ;
function  setError(){
    var obj=document.getElementById( mapsearch );
        obj.setValue(txt);
        obj.setStyle( color ,  red ); 
}
function valform(){
    var obj=document.getElementById( mapsearch );
    var val = obj.getValue();
    if(val!=   &&  !isNaN(val) && val.length>2 ){ 
        return true;
    } else {
        setError();
        (new Dialog()).showMessage( Zip Required ,  Please enter your zip code. );
        return false;
    }
}



...

I found a method that while not very elegant it is simple and works pretty well using serialize().

my form code snippet:

<select name="state" id="states" class="required">

    <option value=""></option> 
    <option value="AL">Alabama</option>
    <option value="AK">Alaska</option>
    <option value="AZ">Arizona</option>
    <option value="AR">Arkansas</option>

</select>

<input value="radio1" type="radio" name="radioPicks" class="radio"/>
<input value="radio2" type="radio" name="radioPicks" class="radio"/>
<input value="radio3" type="radio" name="radioPicks" class="radio"/>
<input type="hidden" name="radioPicks" value="">

The FBJS needed to get this to work:

<script type="text/javascript">
<!--



function checkForm(form) {

    var params=form.serialize();

    if (params.state.length>0 && params.radioPicks!="")

        return true;

    else
        var myDialog = new Dialog(Dialog.DIALOG_POP);
    myDialog.showMessage( Almost Done! ,  Please complete all fields , button_confirm= Close );

    return false;
} 
-->
</script>

The key to this validation method relies on a empty option tag to return "" for the selected tag value and a "" for the radio buttons. I added a hidden input and named it the same name as the radio buttons to add its data to the array returned. the "" value is used in the conditional to check and say if these fields are not empty give the form the ok to send the info to the server. I hope this helps.