套接字。io & express: 404未找到

My app.js

我app.js

const express = require('express'),
      morgan = require('morgan'),
      bodyParser = require('body-parser'),
      path = require('path'),
      mongoose = require('mongoose'),
      app = express(),
      config = require('./config'),
      Note = require('./models/note'),
      server = require('http').createServer(app),
      io = require('socket.io')(server),
      socket = io.socket;

mongoose.connect('mongodb://'+config.db.host+'/'+config.db.name);

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
// Serve static assets
app.use(express.static(path.resolve(__dirname, '..', 'build')));

app.use(function(req, res, next) {
  const allowedOrigins = [
    'https://127.0.0.1:8000',  
    'https://localhost:8000',  
    'https://127.0.0.1:3000',  
    'https://localhost:3000'];
  const origin = req.headers.origin;
  if(allowedOrigins.indexOf(origin) > -1){
    res.setHeader('Access-Control-Allow-Origin', origin);
  }
  //res.header("Access-Control-Allow-Origin", "127.0.0.1 localhost");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  res.header('Access-Control-Allow-Credentials', true);
  next();
});
const express = require('