How to hide seen on facebook chat automatically

NOTE  : this method is working only on web virsion

1: the first is install given bellow extension.
                            
                                 ADD TO FIREFOX
                                                          OR 
                                 ADD TO CHAROME

2: choose and install according to browser type.
3: after installing restart browser.
4: open your facebook account and see option will not visible to your friend while doing chating.
                                   

Methode 2nd : 
This is simple process almost everyone knows.
if you don't want to install any extension then the option availble for you , by it doing manually

> when someone send you a massege then go to inbox area.
> read the massege after the click mark as unread option

now enjoy (Y) i hope you like it.