socket.io和express routing - 如何设置

Question

我正在使用： 表达：v4.16.1 socket.io：v2.0.3

app.js

#include<iostream>
#include<vector>
#include <functional>

int f1(int &x)
//should I return lambda from function ? std::function<decltype (...) f1? 
{
    return [x](int &y) ->int
    {return x * y;} ;

}

int main()
{
  int y = { 3 }, z = { 4 };
    int x=f1(y)(z);
    std::cout<<x<<"\n";
    return 0;
}

现在， index.js ：

中每次使用expres路由器

var express = require('express');
var app = express();
var io = require('socket.io').listen(app.listen(port));

var index = require('./index.js');
app.use('/', index);

io.on('connection', function(socket){//connection stuff});

断开我建立的socket.io连接...如何将socket插入表达路由器？