如何利用Node.js与JSON搭建简单的动态服务器

<form id="registerForm">
 <div>
  <label for="">用户名：<input type="text" name="name" id=""></label>
 </div>
 <div>
  <label for="">密码：<input type="password" name="password" id=""></label>
 </div>
 <div>
  <button type="submit">注册</button>
 </div>
</form>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
let $form = $('#registerForm')
$form.on('submit', (e) => {
 e.preventDefault()
 const name = $form.find("input[name=name]").val()
 const password = $form.find('input[name=password').val()
 console.log(name, password)
 // pass AJAX post data
 $.ajax({
  method: 'post',
  url: '/register',
  contentType: 'text/json; charset=UTF-8',
  data: JSON.stringify({
   name, // name: name 
   password // password: password
  })
 }).then(() => {
  alert('注册成功')
  location.href = '/sign_in.html'
 }, () => {})
})
</script>

<form id="signInForm">
 <div>
  <label for="">用户名：<input type="text" name="name" id=""></label>
 </div>
 <div>
  <label for="">密码：<input type="password" name="password" id=""></label>
 </div>
 <div>
  <button type="submit">登录</button>
 </div>
</form>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
 let $form = $('#signInForm')
 $form.on('submit', (e) => {
  e.preventDefault()
  // get name password
  const name = $form.find("input[name=name]").val()
  const password = $form.find('input[name=password').val()
  // pass AJAX post data
  $.ajax({
   method: 'POST',
   url: '/sign_in',
   contentType: 'text/json; charset=UTF-8',
   data: JSON.stringify({
    name,
    password
   })
  }).then(() => {
   alert('登录成功')
   location.href = '/home.html'
  }, () => {})
 })
</script>

<p>
 {{loginStatus}}
</p>
<p>
 你好,{{user.name}}
</p>
<p>
 <a href="sign_in.html">登录</a>
</p>

var http = require('http')
var fs = require('fs')
var url = require('url')
var port = process.argv[2]

if (!port) {
 console.log('请输入指定端口。如：\nnode server.js 8888')
 process.exit(1)
}

var server = http.createServer(function (request, response) {
 var parsedUrl = url.parse(request.url, true)
 var pathWithQuery = request.url
 var queryString = ''
 if (pathWithQuery.indexOf('?') >= 0) {
  queryString = pathWithQuery.substring(pathWithQuery.indexOf('?'))
 }
 var path = parsedUrl.pathname
 var query = parsedUrl.query
 var method = request.method

 /******** main start ************/
 // 读取 session 文件,转化为对象
 const session = JSON.parse(fs.readFileSync('./session.json').toString())

 if (path === '/sign_in' && method === 'POST') {
  // 读数据库
  let userArray = JSON.parse(fs.readFileSync('./database/users.json'))
  const array = []
  // 每次接受数据就添加进数组
  request.on('data', (chunk) => {
   array.push(chunk)
  })
  request.on('end', () => {
   // 转化字符串
   const string = Buffer.concat(array).toString()
   // 在转化为对象
   const obj = JSON.parse(string)
   // 找到符合的 user
   const user = userArray.find(user => user.name === obj.name && user.password === obj.password) // 成功返回符合的对象，失败返回undefined
   if (user === undefined) { // 失败
    response.statusCode = 400
    response.setHeader('content-Type', 'text/JSON; charset=UTF-8')
    response.end(`{"errorCode":4001}`)
   } else { // 成功
    response.statusCode = 200
    // 设置 Cookie
    const random = Math.random()
    session[random] = {
     user_id: user.id
    }
    // 写入数据
    fs.writeFileSync('./session.json', JSON.stringify(session))
    response.setHeader("Set-Cookie", `'session_id=${random}; HttpOnly'`)
    response.end()
   }
  })
 } else if (path === '/home.html') {
  // 获取 Cookie
  const cookie = request.headers['cookie']
  let sessionId
  try { // 读取 Cookie 中的 id 值
   sessionId = cookie.split(';').filter(s => s.indexOf('session_id=') >= 0)[0].split('=')[1]
  } catch (error) {}
  if (sessionId && session[sessionId]) {
   // 从 session 中读取对应的值
   const userId = session[sessionId].user_id
   // 读数据库
   let userArray = JSON.parse(fs.readFileSync('./database/users.json'))
   // 找到符合的 user
   let user = userArray.find(user => user.id === userId)
   const homeHtml = fs.readFileSync('./public/home.html').toString()
   let string
   if (user) {
    string = homeHtml.replace('{{loginStatus}}', '已登录').replace('{{user.name}}', user.name)
    response.write(string)
   }
  } else {
   // 读取源文件内容
   const homeHtml = fs.readFileSync('./public/home.html').toString()
   // 替换文字
   const string = homeHtml.replace('{{loginStatus}}', '未登录').replace('{{user.name}}', '')
   response.write(string)
  }
  response.end()
 } else if (path === '/register' && method === 'POST') {
  response.setHeader('Content-Type', 'text/html; charset=UTF-8')
  // read database
  let userArray = JSON.parse(fs.readFileSync('./database/users.json')) // read database
  const array = []
  request.on('data', (chunk) => {
   array.push(chunk)
  })
  request.on('end', () => {
   // convert string
   const string = Buffer.concat(array).toString()
   // convert obj
   const obj = JSON.parse(string)
   // last user id
   const lastUser = userArray[userArray.length - 1]
   // new user
   const newUser = {
    id: lastUser ? lastUser.id   1 : 1,
    name: obj.name,
    password: obj.password
   }
   userArray.push(newUser)
   // write data
   fs.writeFileSync('./database/users.json', JSON.stringify(userArray))
  })
  response.end()
 } else {
  response.statusCode = 200
  let content
  // setting index
  const filePath = path === '/' ? '/index.html' : path
  // judge type
  const index = filePath.lastIndexOf('.')
  const suffix = filePath.substring(index)
  const fileType = {
   '.html': 'text/html',
   '.css': 'text/css',
   '.js': 'text/javascript'
  }
  response.setHeader('Content-Type', `${fileType[suffix] || "text/html"};charset=utf-8`)
  try {
   content = fs.readFileSync(`./public${filePath}`)
  } catch (error) {
   content = '文件路径不存在'
   response.statusCode = 404
  }
  response.write(content)
  response.end()
 }

 /******** main end ************/
})

server.listen(port)
console.log('监听 '   port   ' 成功！请输入下列地址访问\nhttp://localhost:'   port)