How can I change sizes in pixels of a div and all its child elements?

I'm trying to perform something like a zoom or scale function but I need to be able to retrieve the new top, left, width and height values in pixels.

I tried scale and visually it transformed everything in the div but when I checked the computed styles they were unchanged.

How can I scale a div and all it's child elements, then in javascript retrieve all the new position and dimension style values specifically in pixels?

 

I've got it: getBoundingClientRect works fine.