我为此所做的是维护一个数据库模型(我使用的是Mongoose)，其中包含已连接用户的userId和socketId.您甚至可以使用全局数组来执行此操作.从客户端通过套接字连接，与userId一起发出事件

What i did for this was to maintain a database model(i was using mongoose) containing userId and socketId of connected users. You could even do this with a global array. From client side on socket connect, emit an event along with userId

socket.on('connect', function() {
    socket.emit('connected', userName); //userName is unique
})

在服务器端，

var Connect = require('mongoose').model('connect');; /* connect is mongoose model i used to store currently connected users info*/
socket.on('connected', function(user) { // add user data on connection
    var c=new Connect({
        socketId : socket.id,
        client : user
    })
    c.save(function (err, data) {
        if (err) console.log(err);
    });
})
socket.on('disconnect', function() { //remove user data from model when a socket disconnects
    Connect.findOne({socketId : socket.id}).remove().exec(); 
})

通过这种方式始终存储已连接的用户信息(当前使用的socketId).每当您需要获取用户当前的socketId时，都将其提取为

This way always have connected user info(currently used socketId) stored. Whenever you need to get a users current socketId fetch it as

Connect.findOne({client : userNameOfUserToFind}).exec(function(err,res) {
    if(res!=null)
        io.to(res.socketId).emit('my message', msg);
})

我在这里使用了猫鼬，但您甚至可以在此处使用一个数组，并使用过滤器从该数组中获取用户的socketId.

I used mongoose here but you could instead even use an array here and use filters to fetch socketId of a user from the array.