detect-js.twig

 {% if js is not defined or not js %}
        <script>
            document.cookie = "js=1";
            location.reload(true); //Refreshes the page
        </script>
    {% endif %}
    {% if js is not defined or js %}
        <noscript>
            <meta http-equiv="Set-Cookie" content="js=0">
            <meta http-equiv="Refresh" content="0">
        </noscript>
    {% endif %}

js_detection.php

<?php

add_action( 'timber/context', function ( array $context ) {
	if ( isset( $_COOKIE, $_COOKIE['js'] ) ) {
		$context['js'] = (bool) $_COOKIE['js'];
	}

	return $context;
} );