Nodejs Part5

Simple-User-List-Class-Solution

中间件

express 中间件的调用流程

express中间件的格式

next函数的作用

const nw = function(req,res,next) {
    console.log("这是一个中间件函数");
    next();
}

app.use(nw);

练习

npm init
npm i express && npm i nodemon -D

index.js

const express = require("express");
const app = express();
const PORT = 8000;
// 定义一个最简单的中间件函数
function mw(req, res, next) {
    console.log("This is a middleware function");
    next();
};
// 注册成全局中间件
app.use(mw);
app.use((req,res,next) => {
    console.log("This is the second middleware");
    next();
})
app.get("/home",(req, res) => {
    console.log("Home Page");
    res.send("home page");
});
app.get("/users",  (req, res) => {
    console.log("users Page");
    res.send("users page");
})
app.listen(PORT, () => console.log("server is running on http://127.0.0.1:8000"));