socket.io在for循环中使用socket.on执行函数

Question

I have some code for an online multiplayer game using socket.io . At one point, clients send data to the server, to receive and process this data I have a socket.on inside a for loop.

Server:

function callBack(hand, upCards) {
    return function() {
      io.to('game_room').emit('log', 'callback');
      players[i].socket.off('swapdone', runSwap);
      players[i].swapped = true;
      io.to('game_room').emit('log', 'call doswap');
      doSwap(i, hand, upCards);
    };
};

for (i = 0; i < players.length; i++ ){
    players[i].socket.on('swapdone', function(hand, upCards) {
      return callBack(i, hand, upCards);
    });
};

hand and upCards are arrays sent from the client using socket.emit

Initially my problem was due to not using a callback function to avoid the closure issue, however now I've added a separate callBack function to fix this.

The problem now is that when the client sends the 'swapdone' signal, the code inside the callBack function is not executed. I've tried moving functions around but I always get either the closure-callback problem, or the function doesn't execute.

What am I missing?

Answer 1

callBack takes two parameters, you pass three arguments. i should be the first parameter of the function. Additionally you have to properly declare i :

for (let i = 0; i < players.length; i++ ){

Additionally the inner function in callBack is useless, as it does nothing. Just remove that.

---

How I would do that:

 function callBack(i) {
  return function(hand, upCards) {
    io.to('game_room').emit('log', 'callback');

    players[i].socket.off('swapdone', runSwap);
    players[i].swapped = true;

    io.to('game_room').emit('log', 'call doswap');

    doSwap(i, hand, upCards);
  };
}

for (let i = 0; i < players.length; i++ ){
 players[i].socket.on('swapdone', callBack(i));
}