Check javascript is on or off through php

I wan to check the client browser is javascript enable or disable. it it is disable then how can i enable it for run my javascript validation?

the only way I know of is to set a test cookie, then reload the page (or go to a new one) and test to see if the cookie was set.
i.e. set the cookie when user goes to login form and on submission check if it was set.

and No, you cannot 'enable' it if the client browser has it disabled.