how to do autocomplete="off" at form level in JSF

A real quick solution with Javascript would be (assuming you have got jQuery loaded):

<script>
    $(function(){
        $("#form").attr("autocomplete", "off");
    });
</script>

If you want to stay with vanilla Javascript, you can do:

<script>
    document.addEventListener("DOMContentLoaded", function(){
        document.getElementById("form").setAttribute("autocomplete", "off");
    });
</script>

Note: For the second solution make sure your browser is covered here: https://developer.mozilla.org/en-US/docs/DOM/Mozilla_event_reference/DOMContentLoaded#Browser_compatibility If not you might be better off using the first solution.