captcha.pt

<span tal:define="name name|field.name;
        css_class css_class|field.widget.css_class;
        oid oid|field.oid;
        style style|field.widget.style;
        "
         tal:omit-tag="">
    <img style="height:30px; width:auto; margin-bottom:5px;" src="${cstruct}">
    <input type="text" name="${name}" value=""
             tal:attributes="class string: form-control ${css_class or ''};
            style style;
            attributes|field.widget.attributes|{};"
           id="${oid}"/>
<script>
    deform.addCallback(
            '${oid}',
            function (oid) {
                $("#" + oid).on('input', function (evt) {
                    $(this).val(function (_, val) {
                        return val.toUpperCase();
                    });
                });
            });
</script>

</span>