how to filter text for html code example

Example: js filter text

<script>
    $('input[name="search_field"]').on("keyup", function() {
        filtrate($(this).val().toLowerCase());
    });

    function filtrate(searched) {
        $(".filter-key > h3").filter(function() {
            var isHidden = ($(this).text().toLowerCase().indexOf(searched) > -1) ? 'block' : 'none';
            $('.filter-key').css('display', isHidden);
        });
    }
</script>