Nodejs initial experience

Nodejs Detailed explanation

One 、 The front-end tool VsCode install

1. Download from the official website ：https://code.visualstudio.com/
2. Can be installed
3. Search plug-ins ：Chinese Sinicization
4. Create folder locally —> And then in vscode Open folder in
5. Modify font size and other settings

Two 、Nodejs Installation

1. Download from the official website ：http://nodejs.cn/
2. Fool installation , always next Just fine
3. Verify that the installation has been successful ：
   • cmd
   • node -v
   • The version number appears ：v18.4.0 Installation succeeded

3、 ... and 、Nodejs Detailed explanation

1、nodejs summary

1. Nodejs amount to java Installed during programming jdk;
2. Chrom V8 engine ： When the installation is good nodejs after , Automatically installed in the system , hold js The file is interpreted to the operating system . amount to jvm： hold class Bytecode files are interpreted to the operating system .
3. Node It is a let. JavaScript Development platform running on the server , It makes JavaScript Become and PHP And so on .
4. In a nutshell ,**Node.js It's running on the server side JavaScript ** . The underlying structure is ：javascript, file extension ：js
5. Node.js It's an event driven I/O Server side JavaScript Environmental Science .

2、nodejs introduction

1. Create folder
2. vscode Open folder in
3. Create a new one js file

console.log("hello xqh");

Print directly on the terminal

：node hello.js

ps: If it appears, say “node Unrecognized , Not internal instructions ” problem , Try closing it vscode, And then in vscode Properties of the , Check open as administrator , Can solve .

3、node Implement request response

// The import module is  require 
const http = require('http');

//1： Create a httpserver service 
http.createServer(function(request,response){
    
    // How do browsers know hello server
    response.writeHead(200,{
    'Content-type':'text/plain'});// Tell the browser how to parse this content 

    // Output content to the browser 
    response.end("hello server!");
}).listen(8888);
console.log(" The service you started is ：http://localhost:8888  Started successfully ！");
//2： Monitor one port 8888
//3： Start the running service  node httpserver.js
//4： Access in browser http://localhost:8888

4、node operation Mysql database

1. cmd In the command ：npm install mysql

• download mysql Related dependencies , The corresponding package will appear in the folder

2. // Import mysql Dependency package ,mysql Modules belonging to third parties 
   var mysql = require("mysql");
   
   //1： Create a mysql Of Connection object 
   //2： Configure data connection information 
   var connection = mysql.createConnection({
         
       host:"127.0.0.1",
       port:3306,
       user:"root",
       password:"123456",
       database:"testdb"
   });
   //3： Open up connections 
   connection.connect();
   //4： perform curd
   connection.query("select * from kss_user",function(error,results,fields){
         
       if(error)throw error;
       console.log("results=",results);
   });
   //5： Close the connection 
   connection.end();
   //6： function node db.js  See the effect