Reactivate previously activated window/program applescript?

I have a script that activates firefox, refreshes the page, waits 60 seconds, then does it again, in an infinite loop. How would I get it to go back to what was active before?

So say I have firefox in the background with a question about Applescripting on StackOverflow up, but while I wait for a response, I'm playing a game. How do I get it to, after going to firefox and refreshing, come back to the game?

Code:

i="0"

while [ $i == 0 ]

do

osascript -e 'tell application "Firefox" to activat开发者_如何学Pythone'

osascript -e 'tell application "System Events" to key code 15 using command down'

pause 10

go back to previous window

sleep 60

done

---

Since you're already using System Events, use it to hide the application.

tell application "System Events" to keystroke "h" using command down