Modern Full-Stack Development

 The Big Kahuna: tileClick()
Now we come to what is the longest, probably most complex (though it’s still nothing 
overly complicated!) and certainly key bit of code that makes BattleJong tick: the one that 
gets called any tile you click a tile:
tileClick : function(inLayer: number, inRow: number,
  inColumn: number) {
Chapter 11   time for fun: BattleJong, the Client

---

336
The tileClick() method is passed the layer, row, and column of the tile that the 
player clicked. That’s all it needs to do its work. But, before it even gets to the real work, 
there are a few trivial rejections that need to be done:
if (this.state.gameState !== "playing") {
  return;
}
The board isn’t visible until gameState is either “playing” or “gameOver”, but in 
the latter case, we don’t want the player to be able to click tiles, so we’ll abort early if 
gameState isn’t “playing”.
Next, we need to determine if a tile can be selected:
if (!this.state.canTileBeSelected(inLayer, inRow, inColumn)) {
  return;
}
The canTileBeSelected() is a helper function that tells us whether a tile is free, in 
terms of Mahjongg rules. Let’s jump over to that function now.