simple and good :)

It works well with wordpress 4.8 !

If you get this error "Warning: Missing argument 2 for wp_register_script(), called in /home/mhd-01/www.jayincucina.com/htdocs/wp-content/plugins/wp-whatsapp-chat/whatsapp-chat.php on line 143 and defined in /home/mhd-01/www.jayincucina.com/htdocs/wp-includes/functions.wp-scripts.php on line 145"

simply edit the file whatsapp-chat.php at line 143 in this way:

the original line is: wp_register_script('whatsapp-chat-admin-js');

you must edit in this way: wp_register_script('whatsapp-chat-admin-js','');