允许CORS进入NodeJS

我定义了我的Express js应用程序:

const express = require('express')
var history = require('connect-history-api-fallback');
const path = require('path')
const http = require('http')
const socketio = require('socket.io')

require('./db/mongoose')
const userRouter = require('./routers/user')

const publicDirPath = path.join(__dirname, '../public')
const app = express()

app.use(express.static(publicDirPath))
app.use(history({
  index: '../public/index.html'
}))
app.use(express.static(publicDirPath))
app.use(express.json())
app.use(userRouter)

const server = http.createServer(app)
const io = socketio(server)

io.on('connection', socket => {
  console.log('New WebSocket connection')

  socket.on('join', () => {
    socket.emit('message', 'Welcome to the app')
  })
})

module.exports = server

然后使用index.js文件:

const app = require('./app')

const port = process.env.PORT

app.listen(port, () => {
  console.log(`Server is up on port ${port}`)
})

当我运行应用程序并从同一端口发送请求时,一切正常。但当我尝试从不同的本地主机端口(如8080)发送请求时,会出现跨源错误。 我试着安装cors包并按如下方式使用它:

const cors = require('cors')

app.options('*', cors())
app.use(cors());

得到了同样的结果。

app.use(cors({
  origin: 'http://localhost:8080'
}));

结果还是一样。

我做错了什么?我该怎么做?