Event onComplete executes if the SSJS code has completed successfully.

So it's exactly what you are looking for - as Tim pointed out. 

 One of your divs will be the refresh target of the onclick event, so that one is taken care of. SInce the SSJS cannot 'push' a refresh to the second div, you have to make the client ask for it. The oncomplete code will execute once the refresh of the first div is complete and that's where you want to do a XSP.partialRefreshGet("clientside id of second div").

 

Rich