WordPress experiment. Toggle debug from admin bar

toggle-debug.php

<?php
/*
Plugin Name: Toggle Debug
Description: Proof-of-concept for an admin-bar debug mode toggle. Needs some UX love.
*/
/*
// In wp-config.php, wrap debug constants in a cookie conditional
if ( isset( $_COOKIE['wp-debug'] ) && $_COOKIE['wp-debug'] == 'on' ) {
	define('WP_DEBUG', true);
}
if ( isset( $_COOKIE['script-debug'] ) && $_COOKIE['script-debug'] == 'on' ) {
	define('SCRIPT_DEBUG', true);
}
*/

$toggle_debug = new Toggle_Debug();
class Toggle_Debug {

	function __construct( ) {

		add_action( 'init',           array( $this, 'init' ), 1 );
		add_action( 'admin_bar_menu', array( $this, 'admin_bar_menu' ), 100 );

	}

	function init() {
		foreach ( array( 'wp', 'script' ) as $type ) {

			if ( isset( $_GET['toggle-'. $type .'-debug'] ) ) {
				if ( 'on' == $_GET['toggle-'. $type .'-debug'] ) {
					//turn off
					setcookie( $type. '-debug', '', time()-3600, '/');
					unset( $_COOKIE[ $type. '-debug' ] );
				}
				if ( 'off' == $_GET['toggle-'. $type .'-debug'] ) {
					//turn on
					setcookie(  $type. '-debug', 'on', time()+(60*60*24*30), '/');

				}
				wp_redirect( remove_query_arg( 'toggle-'. $type .'-debug' ) );
				exit;
			}

		}
	}

	function admin_bar_menu( $wp_admin_bar ) {

		$wp_admin_bar->add_menu( array(
			'id'    => 'debug-mode',
			'title' => 'Debug Mode',
		) );

			$wp_admin_bar->add_menu( array(
				'parent' => 'debug-mode',
				'id'     => 'debug-mode-wp',

				// labeling is ambiguous and should be clarified. describes current status in both title and link
				// thus the action in the link has to be inverted ( see init(), if it says 'on' we turn it off...)
				'title'  => __( 'WP_DEBUG: ' . ( WP_DEBUG ? 'on' : 'off' ) ),
				'href'   => add_query_arg( 'toggle-wp-debug', ( WP_DEBUG ? 'on' : 'off' ) ),
			) );
			$wp_admin_bar->add_menu( array(
				'parent' => 'debug-mode',
				'id'     => 'debug-mode-script',
				'title'  => __( 'SCRIPT_DEBUG: ' . ( SCRIPT_DEBUG ? 'on' : 'off' ) ),
				'href'   => add_query_arg( 'toggle-script-debug', ( SCRIPT_DEBUG ? 'on' : 'off' ) ),
			) );

	}

}

//eof

A quick test (in case you're on a perfectly functioning site) is to enqueue a script inside init(), that's too early so if debug is on, it'll notify you.

@trepmal is it work in progress? Coz it ain't working at my side.

@ahmadawais see title: "WordPress experiment"

Works like a charm! Nice work :)