Question

Is it possible to do checking and verification of JavaScript state in a browser ?

Answer 1

At the top of your index.php you could do something like

<script type="text/javascript">
    window.location = '/index_with_js.php'
</script>

So, if the browser had JS enabled, it would be redirected to a special index page, which could in turn set a session variable, e.g. $_SESSION['has_js'] = true;

If the browser doesn’t have JS enabled, the page won’t be directed, so $_SESSION['has_js'] won’t ever be set.