Question

io.sockets.on('connection', function (socket) {                
    socket.on('requestGame', function (data) {

    for (var game in games)
        if (game.player2 === undefined) {
            game.player2 = socket;
            socket.emit('gameStart', { game_id: game.game_id, turn: !p1_turn }); // works
            game.player2.emit('gameStart', { game_id: game.game_id, turn: !p1_turn }); // doesn't work

为什么其中一条线路有效而另一条线路没有？

这是错误

game.player2.emit('gameStart', { game_id: game.game_id, turn: !game.p1_tur
             ^
TypeError: Cannot call method 'emit' of undefined

Answer 1

for (var a in b)语法遍历b的键。每次循环时，a都是一个字符串，而不是你可能正在寻找的b的值。

因为它是一个字符串和一个文字，所以附加一个属性将立即对它没有任何影响。您无法在Javascript中更改字符串和数字等文字。

'hello'.foo = 'world';
console.log('hello'.foo); // undefined
var str = 'hello';
str.foo = 'world';
console.log(str.foo); // undefined

你可能想做的是

    for (var key in games)
        var game = games[key];
        if (game.player2 === undefined) {
            game.player2 = socket;
            socket.emit('gameStart', { game_id: game.game_id, turn: !p1_turn }); // works
            game.player2.emit('gameStart', { game_id: game.game_id, turn: !p1_turn }); // doesn't work

Socket.io套接字句柄

1 个答案: