javascript - 回调函数socket.io + node.js

Question

有客户端和服务器端代码:

客户:

socket.on('connect',  function() {
        showSystemMessage('Connected.');

        socket.emit('setuser', wm, function(data){
            console.log(data);
            socket.emit('whoisonline', wm, function(data){
                getOnlineFriends(data);
            });
        });
    });

服务器:

io.on('connection', function(socket) {
        socket.on('setuser', function (data, cb) {
            cb(data);
        });
});

我收到错误:

TypeError: undefined is not a function on line 18

第 18 行:

socket.on('setuser', function (data, cb) {
     cb(data); // Line 18
});

然后我尝试了你的解决方案，我得到:

TypeError: undefined is not a function in line 35

socket.on('whoisonline', function (data, cb) {
            redis.sinter('user.friend:' + data.id, 'onlineusers', function(error, intersection) {

                friends.online = intersection;
                friends.total  = intersection.length;

                if(friends.total > 0){
                    intersection.forEach(function(entry) {
                        var socketid = clients[entry];
                        io.sockets.connected[socketid].emit('in', { id : data.id, total : friends.total });
                    });
                }

                cb(friends); // Line 35
            });
        });

Answer 1

就我而言，以下工作有效:

• 在服务器端

  socket.on('setuser', (name, cb) => { cb(name); });
  

• 在客户端

  socket.emit('setuser', 'user data', r => { console.log(r); });