Google Maps API - For Real Estate

How do we know programatically what portion of the map is visible at any given time? For example:

When I load a map I set the center so I know which point I am on and will know what properties to load. However, when a user drags the map along or zooms into a smaller section of the map. How do I know which properties to plot at that point? How will know what exactly the user is looking at?

Thanks.

 

Found the answer:

First use map.getBounds()
Then bounds.getSouthWest() and bounds.getNorthEast()

 

I really did search a bit for the solution. Anyway thanks for sharing the answer.