Touch: identifier property

someElement.addEventListener("touchmove", (e) => {
  // Iterate through the list of touch points that changed
  // since the last event and print each touch point's identifier.
  for (let i = 0; i < e.changedTouches.length; i++) {
    console.log(
      `changedTouches[${i}].identifier = ${e.changedTouches[i].identifier}`,
    );
  }
});