Laravel 拉威尔+；插座，无'；访问控制允许原点'；

我用的是拉拉贡。第一次在laravel使用插座。我正在尝试联机获取当前数据，但在控制台中启动服务器时，我看到错误：

Access to XMLHttpRequest at 'http://zernovka.test:7777/socket.io/?EIO=3&transport=polling&t=NNdd1z3' from origin 'http://zernovka.test' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
GET http://localhost:7777/socket.io/?EIO=3&transport=polling&t=NNdd1tW net::ERR_FAILED

My app.js代码：

var app = require('express')();
var http = require('http');
var server = http.createServer(app);
var io = require('socket.io')(server);
let port = 7777;

server.listen(port, function () {
  console.log('Using:' +port);
});


var userCount = 0;

io.sockets.on('connection', function (socket) {
  userCount++;
  io.sockets.emit('userCount', { userCount: userCount });
  socket.on('disconnect', function() {
    userCount--;
    io.sockets.emit('userCount', { userCount: userCount });
  });
});

在main.js文件中

var socket = io.connect(':7777');
  socket.on('userCount', function (data) {
  console.log(data.userCount);
});

我怎么能修好它？ 谢谢你的帮助