Using javascript how do I address individual items in a group?

I want to:

Find out how many items are in a group

Address/work with each item in turn

In the documentation ways, I can find ways to address specific types of items in the group but I can’t see anyway to handle them generically:

allPageItems (array of page items contained in the group)

textFrames (array of text frames contained in the group)

allGraphics (array of all graphics contained in the group)

TIA