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Detailed explanation of express framework
2022-07-06 11:36:00 【Advanced diary】
Express
Use express You can quickly create web Web server or API Interface server
1. establish express Of web The server
// Import express
const express = require("express")
// establish web The server
const app = express()
// start-up web The server
app.listen(8088,()=>{
console.log('http://127.0.0.1:8088');
})
2. monitor get/post request
// monitor GET Request and return the response content , The first parameter is the requested url
app.get('/get',(req,res)=>{
//req.query Get request is the parameter sent
console.log(req.query)//http://127.0.0.1:8088/get?name=zs&age=18
//{ name: 'zs', age: '18' }
// call express Provided res.send() Method , Set the returned JSON object
res.send({name:"zs",age:20,gender:" male "})
})
// monitor POST Request and return the response content , The first parameter is the requested url
app.post('/post',(req,res)=>{
// call express Provided res.send() Method , Set the returned JSON object
res.send({name:"zs",age:20,gender:" male "})
})
towards http://127.0.0.1:8088/post The return value of the send request is
{ "name": "zs",
"age": 20,
"gender": " male "}
3. To obtain parameters
// Static parameters
app.get('/get',(req,res)=>{
//req.query Get request is the parameter sent
//http://127.0.0.1:8088/get?name=zs&age=18
res.send(req.query)
//{ name: 'zs', age: '18' }
})
// Dynamic parameters
app.get('/getId/:id',(req,res)=>{
//req.query Get request is the parameter sent
//http://127.0.0.1:8088/getId/12
res.send(req.params)
})
// return
{
"id": "12"
}
// Multiple dynamic parameters
app.get('/getId/:id/:name',(req,res)=>{
//req.query Get request is the parameter sent
//http://127.0.0.1:8088/getId/12/zs
res.send(req.params)
})
// return
{
"id": "12"
"name":"zs"
}
4. middleware
//app.use() The function is to register the global middleware ,app.use('path',function()) The first parameter is the path. If it is / Omission
express There are three kinds of middleware
1. Built in middleware static
2. Custom middleware
3. Third-party middleware (body-parser) ( Interceptor )
app.use(express.static('public'))
app.use(express.static('dome'))
// You can directly access
http://127.0.0.1:8088/index.html
http://127.0.0.1:8088/index.css
http://127.0.0.1:8088/index.js
// Will prioritize public In the document index file , If you can't find it, find dome Medium index file
app.use('/public',express.static('public'))
// To access http://127.0.0.1:8088/public/index.html
// Customize the middleware with global effect Multiple middleware can be defined , The middleware will be called in sequence
app.use(function (req, res, next) {/* Indicates that it matches any route */
console.log(new Date())
next()/* Indicates that the middleware will continue to execute after the matching is completed .*/
})
// Local middleware
let func = function (req, res, next) {/* Indicates that it matches any route */
console.log(new Date())
next()/* Indicates that the middleware will continue to execute after the matching is completed .*/
}
// Multiple local middleware can be defined
app.get('/',func1,func2,(req,res)=>{
res.send('get router by :/')
})
// Use middleware to process request data
app.use(express.json())
app.use(express.urlencoded({extended:false})
// Use third-party middleware (body-parser) ( Interceptor )
1. npm install body-parser
// To middleware
const parser = require("body-parser")
// Register middleware
app.use(parser.urlencoded({extended:false})
//nodejs built-in querystring The module processes the query string and converts the query string into object format
const qs = require("querystring")
console.log(qs.parse(str))
5. nodemon
It can start the modified project less frequently ,nodemon It will automatically restart the project to facilitate development and testing
npm install -g nodemon
Use nodemon app.js To run the project , no need node app.js
6. route
1. Mount in the original way
const express = require("express")
const app = express();
// Mount route
app.get('/',(req,res)=>{
res.send('get router by :/')
})
app.post('/',(req,res)=>{
res.send('post router by :/')
})
app.listen(8088,()=>{
console.log("http://127.0.0.1:8088");
})
2. Use express route
// stay router.js Create a routing object in
const express = require("express")
const router = express.Router();
// Mount specific routes
router.get('/user/list',(rep,res)=>{
res.send("GER user list")
})
router.post("/user/add",(req,res)=>{
res.send("POST user add")
})
// Export routing objects out
module.exports = router
// stay index.js Reference route in
const express = require("express")
const app = express()
// Import routing module
const router = require("./router")
// Register routing module
app.use(router)
app.listen(8088,()=>{
console.log("http://127.0.0.1:8088");
})
//app.use('/api',router)// Add a uniform prefix to the route http://127.0.0.1:8088/api/user/add
7. To write get/post Interface
const express = require("express");
const app = express()
const router = express.Router()
app.use(express.urlencoded({extended:false}))
router.get('/get',(req,res)=>{
// Request data sent by the client
const query = req.query;
res.send({
status:0,//0 It means success ,1 It means failure
msg:"GET The request is successful ",// Description of the State
data:query// Data that needs to be responded to the client
})
})
router.post('/post',(req,res)=>{
// Request data sent by the client
const body = req.body;
// Configure the middle price of parsing form data
res.send({
status:0,//0 It means success ,1 It means failure
msg:"POST The request is successful ",// Description of the State
data:body// Data that needs to be responded to the client
})
})
app.use(router);
app.listen(8088,()=>{
console.log("get request ");
})
8.cors Cross domain solution
const express = require("express");
const cors = require("cors")
const app = express()
// Use third-party middleware to solve cross domain
app.use(cors())
// Customize cors Set up cross domain requests
var cors = function(req,res,next()){
res.header('Access-Control-Allow-Origin', 'http://localhost:8088');// Request address
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');// Request mode
res.header('Access-Control-Allow-Headers', 'Content-Type');// Request header
next()
}
app.use(cors)
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