How to use inner html value or data in php from javascript(innerHTML)?

inner html value or data in php from javascript(innerHTML)

<html>
<body>

<p id=”demo”>use inner html value in php(innerhtml)</p>

<script>

var jassi = document.getElementById(“demo”).innerHTML;
//document.write(jassi);

</script>

<?php
$jassi = ‘<script>document.write(jassi);</script>’;
echo $jassi;