切换按钮以展开/折叠div

I have two divs next to each other and would like to use the toggle function to collapse one div (Sidebar) horizontally while expanding the other (Map) to take full width of the former. I would then need the toggle to bring back both divs to their original widths/positions. I can get it to do the first operation but I have no clue on how to do the reverse. See I have two divs next to each other and would li