Untitled

<html>
<body>

    <?php
        int cont = 0;
    ?>

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js" type="text/javascript"></script>
    <script>

        req()
        {
            $.ajax({url: "func.php"}, success: function(data) {
                document.getElementById("p1").innerHTML = data;
            });
            setInterval(req(), 2000);
        };

        $('document').ready(function(){
            setInterval(req(), 2000);
        });

    </script>

    <p id="p1">0</p>
</body>

<?php
    cont++;
    echo cont;
?>