Indesign script (Javascript) to return/select words around insertion point

Consider the following text:

She sells sea shells.

Say my insertion point is currently at a blank space between two words, i.e.

app.selection[0].characters.length < 1

I need to select or return the two words flanking the insertion point on either sides. So, if the insertion point is between sells and sea, I need the selection to be sells sea, if it's between sea and shells, I need the selection to be sea shells, and so on. I tried using the parent property but it's not giving me any option to return the specific words I need. Any help will be precious!