The internet is divided on this one. I would say that it depends on what you do.
If your battery can still normaly charge while you're working on the device (e.g. background music, note taking, light browsing, e-books or audiobooks) then you're fine.
But if your battery is charging and draining at the same time (e.g. gaming or any other workflow using 80%+ of the resources) then expect that the health of the battery will decline faster.