I have some objects like this: (wordpress attachment object)
attachment.sizes (which is an object and contains:) 
                .full (each contains height and width:)
                     .height
                     .width
                .medium
                       .height
                       .width
                .thumbnail
                          .height
                          .width
And then I have another object:
props.size (which is either "full","medium" or "thumbnail")
Can I in some way write similar to
attachment.sizes.(props.size).height 
To get the height? (That did not work when I tried)
attachment.sizes[props.size].heightshould work.