Code snippet 16 - For multiplayer space invaders article

server.js

function startDownwardMovement(playerId) {
  let interval = setInterval(() => {
    if (players[playerId] && players[playerId].isAlive) {
      players[playerId].y += PLAYER_VERTICAL_INCREMENT;
      players[playerId].score += PLAYER_SCORE_INCREMENT;

      if (players[playerId].y > SHIP_PLATFORM) {
        finishGame(playerId);
        clearInterval(interval);
      }
    } else {
      clearInterval(interval);
    }
  }, PLAYER_VERTICAL_MOVEMENT_UPDATE_INTERVAL);
}