una/template/form_field_custom_suggestions.html

<div id="__id__" class="__class__">
    __vals__
    <bx_if:input>
        <input type="text" class="bx-def-font-inputs bx-form-input-text" __attrs__ />
    </bx_if:input>
</div>
<bx_if:init>
    <script language="javascript">
        $(function(){
            $('#__id__ input').on('focus', function () {
                $(this).attr("placeholder", "__placeholder__");
            });

            bx_autocomplete_fields('__id__','__url_get_recipients__','__name__',__b_img__,__only_once__,__on_select__);
        });
    </script>
</bx_if:init>