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foreword
Today's applications must be accurate and fast to survive the brutal competition. Also, real-time systems need to do things within a certain time window.
Real-time systems using Node.js scale well and can provide longer-lasting results. We will look at the importance of Node.js in real-time systems in detail.
As we know, Node.js can provide continuous two-way communication in various fields. Whether it's a stock trading platform, a social network, or a forum, Node.js can provide an uninterrupted connection for better communication.
提示：以下是本篇文章正文内容，下面案例可供参考
1. Install node
1. Check the node version: node -v .
2. Create a node project
1. Create folder app
2.cmd /app: npm init -y to initialize the node project
3. Run the node file
1、 cmd /app: node index.js
2、 packge.json：
configuration: "scripts": {
"serve":"node index.js", //---------------------
"test": "echo \"Error: no test specified\" && exit 1"
},
3.npm run serve run
4. Set Taobao Mirror
1. cmd administrator:
2.npm config set registry http://registry.npm.taobao.org/
3.npm config get registry View download source
Five, npm package manager, used to install third-party libraries
1.cmd /app:
1. Installation:
npm i pkg1 pkg2 pkg3 install locally
npm i pkg -g global installation
npm root view -g to view the global installation directory
Use npm i pkg -D for development
npm i pkg -S is used after development and launch
npm i pkg@version specified version installation
npm list View plugins
2. Uninstall:
npm uninstall pkg
npm remove pkg
npm r jquery
3. Update:
npm view jquery versions View historical versions
npm update jquery
4. Install and uninstall help commands:
npm install -h
npm uninstall -h
6. Version introduction:
^3.1.0, the maximum version update is no more than 4.0.0 ^: Indicates that it can be updated
3.1.0: Unable to update
The meaning of the three digits of the XYZ version
X: major version, incompatible update
Y: medium version, add some new content
Z: Minor version, fixed some minor bugs
7. Catalog introduction:
node_modules: addresses of all dependent packages
package.json: project related configuration
scripts: what commands are available in the current project
dependencies: What are the dependencies of the current project
package-lock.json: The cache address of all dependent packages, the next download will be accelerated
npm i : will download all previous cache dependencies
8. Use of templates
1. Third-party modules
npm i pkg
var pkg=require('pkg')
2. Built-in modules
var fs=require('fs')
var http=require('http')
3. Custom modules
Export:
module.exports={'property name': 'property value', 'property name': 'property value'}
import: var utils=require('./utils')
Nine, file reading and writing
1. Synchronous and asynchronous reading
//1、同步读
var fs=require('fs');
console.log(1);
var res=fs.readFileSync("./qiku.txt",'utf-8');
console.log(res);
console.log(2);
//2、异步读取
console.log(6);
fs.readFile('./qiku.txt','utf8',function(err,res){
//如果没有错误结果
if(!err){
console.log(res);
}
})
console.log(8);2. Write synchronously and asynchronously
//同步写
console.log(11);
fs.writeFileSync('./html.txt','web大前端')
console.log(22);
//异步写
console.log(66);
fs.writeFile('./html.txt','nodejs',function(err){
if(!err){
console.log("写入成功");
}
})
console.log(88);10. Server Construction
//引入http模块
let http=require('http');
//引入url:获取路由参数 npm i url
let url=require('url');
//创建服务
// req:request请求； res:response响应
let server=http.createServer(function(req,res){
//从请求中拿到路由参数
let params=url.parse(req.url);
res.statusCode=200; //正确的状态吗
//设置请求头
res.setHeader('Content-Type','application/json;charset=utf-8')
//给前端的响应结果
res.end(`{"errCode":0,"msg":"${params.search}"}`);
})
//开启服务
server.listen(8888,function(){
console.log("服务启动成功");
})
/* 访问:
localhost:8888
127.0.0.1:8888
192.168.13.8:8888
查看本机ip:ipconfig
停止服务:ctrl+c
*/Summarize
The above is what I want to talk about today. This article only briefly introduces the basic use of nodejs, and nodejs provides a large number of functions and methods that allow us to process data quickly and conveniently.