By Jeskson

Source: front end tavern of dada

Request and upload files

GET and POST requests

const express = require('express');

const app = express();

app.set('view', 'pug');

app.get('/', function(req,res){
 // Output response message
 req.send('hello')
});

app.get('/users/:gender', function(req,res){
 // Get route parameters
 let gender = req.params.gender;
 // Get url parameters
 let name = req.query.name;
 // Output response
 res.send('gender='+gender+',name='+name);
});
// Start HTTP server
app.listen(8080, function(){
 console.log('express')
});

The POST request gets the parameters through the body parser template engine and the req.body() function.

const express = require('express');

const bodyParser = require('body-parser');

// Create express program
const app = express();

// Configure view templates
app.set('view engine', 'pug');

// Configure post
app.use(bodyParser.urlencoded({
 extended: true
});

app.get('/create', function(req, res){
 res.render('create.pug');
});

app.post('/create', function(req,res){
// Get user output form message
let name =  req.body.name
let pswd = req.body.password;
res.send('name='+name+",pswd="+pswd);
});
app.listen(8080, function(){
 console.log('express');
});

Upload files

Upload files with the media middleware:

const express = require('express');

const bodyParser = require('body-parser');

const multer = require('multer');

const app = express();

app.set('view', 'pug');

app.use(bodyParser.urlencoded({
 extended:true
}));

const upload = multer({
 dest: 'uploads/'
});

app.get('/create', function(req, res){
 res.render('create.pug');
});

app.post('/create', function(req,res){
// Get user output form information
let name = req.body.name;
let pswd = req.body.password;
res.send('name =' + name + ",pswd="+pswd);
});

app.get('/upload', function(req, res){
 res.render('upload.pug');
});

app.post('/upload', upload.single('photo'), function(req,res){
// Get upload file information
let file = req.file;
res.send(file);
});
// Start http server
app.listen(8080,function(){
 console.log();
});

node server.js

session Introduction

The server will create a session object for the browser. A browser can only have one session. Session is like this. When the user data needs to be maintained, the server program can store the user data in the session of the browser. When the user accesses other programs using the browser, the data can be extracted from the session.

Use of session:

npm install express-session

var session = require("express-session");

app.use(session({
secret: 'keyboard cat',
resave: true,
saveUninitialized: true
}))

Differences between cookie s and session s:

Cookie is to write the user's data to the user's browser and keep the state data at the browser end. When accessing the server, the amount of data transferred is large and the burden is heavy. The user may modify the cookie information, which leads to the server's insecurity.

Session is to write the user's data to the user's session. Different users are identified by different session ID, and keep the session ID in the client's cookie or locally. When the request is sent, the cookie information of the session "ID is attached to distinguish which user's data.

Introduction to restful api

REST infrastructure:

Restful API to create a json data resource file.

var express = require('express');
var app = express();
var fs = require("fs");

app.get('/listUsers", function(req,res){
fs.readFile(dirname + '/' + "users.json", "utf8" ,function(err,data){
 console.log(data);
 res.end(data);
 });
})

var server = app.listen(8081,function(){
var host = server.address().address
var port = server.address().port

console.log();
})

node server.js

Nodemon

nodemon to monitor changes to the node.js application and automatically restart services.

npm install -g nodemon

npm install --save-dev nodemon

nodemon common commands:

nodemon -h or nodemon --help Use help

nodemon --watch path

Monitor current work path

nodemon --ignore

Ignore that some files are monitored

rs

Manual start system

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