Nintendo LABO's Piano - How does it work?

Written By Sanjir Habib On Jan-18th, 2018

Searched for and found the answer here:

The Joy-Con slots into the back, with its IR camera pointed at a small slot just above the rear of the keys. When one is pressed, it pops into view through the slot and reveals small strip of reflective tape – the camera picks this up and plays the relevant note.