If javascript is disabled, hide everything on the page and show a message.

WordPress javascript required

function my_prefix_hide_everything_if_javascript_disabled() {
	?>
	<noscript id="javascript_test">
		<style type="text/css">
			body > * {display:none!important;}
			#javascript_test{
				display:block!important;
			}
		</style>
		<div class="noscriptmsg">
			<?php echo __( 'You don\'t have javascript enabled. Check your browser extensions to see if any might be disabling it.', 'text_domain_here' ); ?>
		</div>
	</noscript>
	<?php
}
add_action( 'wp_footer', 'my_prefix_hide_everything_if_javascript_disabled' );