express(中间件)

• 只要访问一次，就会创建一次时间，当访问了/user 执行两部操作

const express = require('express');
const app = express();
app.use((req, res, next) => {
    console.log(req.url + '访问时间' + Date.now());
    next()
});
app.get('/user', (req, res, next) => {
    console.log('result');
    next();
},(req, res) => {
    console.log("result1");
    res.end("result1");
});
app.listen(3000, ()=>{
    console.log('runing……');
})

• 可以用变量定义中间件

const express = require('express');
const app = express();
let cb0 = (req, res, next) => {
    console.log('Cb0');
    next();
};
let cb1 = (req, res, next) => {
    console.log('Cb1');
    next();
};
let cb2 = (req, res) => {
    res.send('Hello Tom');
};
app.get('/user',[cb0, cb1, cb2]);
app.listen(3000, ()=>{
    console.log("running……");
})

• 访问次数和访问时间

const express = require('express');
const app = express();
let count = 0;
app.use((req, res, next) => {
    console.log(req.url + '访问时间' + Date.now());
    next();
});
app.use((req, res, next) => {
    count ++;
    console.log(count);
    next()
});
app.get('/login',(req, res) => {
    res.end('success');
});
app.listen(3000, ()=>{
    console.log("running……");
})