How to prevent F12 on webpage?

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>

<script>

    $(document).keydown(function (event) {

        if (event.keyCode == 123) {

            return false;

        }

        else if (event.ctrlKey && event.shiftKey && event.keyCode == 73) {

            return false;

        }

    });

    $(document).on("contextmenu", function (e) {

        e.preventDefault();

    });

</script>