J2 employment authorization (EAD) validity?

I am currently on J2 visa which is due to expire on July 31st. I also got EAD which expires the same day. My husband will switch to H1b from J1 in a month or so, which means my J2 becomes invalid and changes to H4. I was wondering if the EAD also expires with the J2 visa expiration or is it valid till july 31st irrespespecitve of J2 validity?