node——模块拆分：路由 - router 控制器 - controller

const http = require('http')
const PORT = 3001

// 控制器
const controller = {
     
  index (req, res) {
     
    res.end('this is index page')
  },
  home (req, res) {
     
    res.end('this is home page')
  },
  _404 (req, res) {
     
    res.end('404 Not Found')
  },
}

// 路由器
const router = (req, res) => {
     
  if (req.url === '/') {
     
    controller.index(req, res)
  } else if (req.url.startsWith('/home')) {
     
    controller.home(req, res)
  } else {
     
    controller._404(req, res)
  }
}

const server = http.createServer(router)
server.listen(PORT, () => {
     
  console.log(`the server is started at port ${
       PORT}`)
})