node和express基础

这一部分介绍了使用express框架操作服务器的一些基础知识，包括：

• response的扩展函数，如res.send()发送字符串、res.sendFile()发送文件、res.json({})响应json对象
• 通过request获取请求数据，如req.method获取请求方式、req.path获取请求路径、req.ip获取请求方ip
• 如何获得get和post方式请求的数据，详细可见《body-parser解析请求体》
• 代码风格，利用next实现操作链，在前一次操作中获取变量供下一次操作使用等

以下是这一部分习题的解答：

Introduction to the Basic Node and Express Challenges

• Meet the Node console

  console.log("Hello World");

• Start a Working Express Server

  app.get('/root', (req, res) => {
    res.send("Hello Express");
  });

• Serve an HTML File

  app.use('/', (req, res) => {
    res.sendFile(__dirname + "/views/index.html");
  });

• Serve Static Assets

  app.use(express.static(__dirname + '/public'));

• Serve JSON on a Specific Route

  app.get('/json', (req, res) => {
    res.json({"message": "Hello json"});
  });

• Use the .env File

  app.get('/json', (req, res) => {
    res.json(process.env.MESSAGE_STYLE=="uppercase"?{"message": "Hello json".toUpperCase()}:{"message":"Hello json"});
  });

• Implement a Root-Level Request Logger Middleware

  app.use('/', (req, res, next) => {
    console.log(req.method+" "+req.path+" - "+req.ip);
    next();
  });

• Chain Middleware to Create a Time Server

  app.get('/now', (req, res, next) => {
    req.time = new Date().toString();
    next(); 
  }, (req, res) => {
    res.json({time: req.time});
  });

• Get Route Parameter Input from the Client

  app.get('/:word/echo', (req, res, next) => {
    res.json({echo: req.params.word});
    next();
  });

• Get Query Parameter Input from the Client

  app.get('/name', (req, res, next) => {
    res.json({name: req.query.first+' '+req.query.last})
  })

• Use body-parser to Parse POST Requests

  app.use(bodyParser.urlencoded({extended: false}));
  app.post('/', (req, res) => {
    res.json(req.body);
  });

• Get Data from POST Requests

  app.use(bodyParser.urlencoded({extended: false}));
  app.post('/name',(req,res,next) => {
    res.json({name: req.body.first+' '+req.body.last});
  });