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Detailed explanation of nodejs
2022-07-06 11:36:00 【Advanced diary】
node.js
install nodejs
https://nodejs.org/zh-cn/
Package manager npm
npm init initialization npm install Download dependency && npm install Download dependency @ Version number // Installation package -S -save Abbreviation Used in the production of ( go online ) In the environment , The package name will be registered in package.json Of dependencies Inside , In the production environment, the dependency of this package still exists ; -D -dev( production ) The package name will be registered in package.json Of devDependencies Inside , Packages that exist only in the development environment -D, Such as babel,sass-loader These parsers devDependencies , These are some packages that we need to use when developing , It only needs to be used in the development phase , You don't need these packages when you really pack them online , Because these tools are just what you use to package code , Is used to identify specific files and codes , Help us produce the final documents dependencies, This needs to be released to the production environment , For example, if you want to run a race based on vue Project , So we need to vue.js To support , And this vue.js Documents need to follow the project to the final production environment -g Global installation npm uninstall Package name // Uninstall package npm run Run the project
nrm
nrm ls // Check the optional download source nrm use name // Switch download source nrm add registry Download source // Add download source nrm del name // Delete download source nrm test// Test Download response time
nvm management node edition
nvm list available // List all the... That can be installed node edition nvm install 17.2.0 //node Version number download nvm ls // Show downloaded node edition Front belt * Is currently in use node edition nvm use 17.2.0 // Use node edition
npx
npx @vue/cli -V amount to npm install @vue/cli -g + vue -V 1、 Temporarily install executable dependent packages , No global installation , Don't worry about long-term pollution . 2、 You can execute commands in dependent packages , The installation is complete and runs automatically . npx create-react-app my-react-app // Download to the temporary directory and delete it automatically after use 3、 Automatic loading node_modules Dependent packages in , Don't have to specify $PATH. node-modules/.bin/mocha --version npx mocha --version 4、 You can specify node edition 、 The version of the command , It solves the problem that different projects use different versions of commands . npx [email protected] -v
modularization
Three ways to export modules module.exports = { function add(a,b){} return a+b } console.log(add(1,2)) } module.exports.name = 'zs' exports.num = 18 Use require The import module const index = require('./index');
fs modular
fs.readFile(path[,options],callback) fs.writeFile(path,' Content ',callback) // Import fs const fs = require('fs') // call fs.writeFile() Method write file // Parameters 1: Write the storage path of the file // Parameters 2: Write the contents of the file , The format is generally utf8 // Parameters 3: Callback function fs.writeFile('./node.txt','asdfsaf',function (err) { if (err) { return console.log(' File write failed ',err.message); } console.log(' File written successfully '); }) // call fs.readFile() Method to read the file // Parameters 1: Read the storage path of the file // Parameters 2: The encoding format used when reading the file , It's usually utf8 // Parameters 3: Callback function , Get the results of failure and success fs.readFile('./node.txt','utf8',function (err,succeed) { if (err) { return console.log(' File read failed ',err); } console.log(' The content of the document is :',succeed); })
dirname
//__dirname Indicates the directory where the current file is located console.log(__dirname); // Output E:\nodeStudy It can be used __dirname+'./node.txt' Splicing file path
path modular
path.join() // Splicing file path path.basename() // Get the file name in the file path path.extname() // Get the file extension name in the path // Import path modular const path = require("path") const pathStr = path.join('a','b','c','..','d/f') console.log(pathStr);//a\b\d\f path.join(__dirname+'/node.txt')// Splicing file path path.fpath = 'a/b/c/index.html' console.log(path.basename(fpath))// Get the file name index.html console.log(path.basename(fpath,'.html'))// Get the file name prefix index console.log(path.extname(fpath))//.html
http modular
// Import http modular const http = require("http") // establish web Server instance const serve = http.createServer() // Bind to the server instance request event , Listen for client requests // req For the object of the request , Contains data and properties related to the client //res The response object , It contains data and attributes related to the server serve.on('request',(req,res)=>{ console.log(req.url,req.method); console.log('request event '); res.setHeader("Content-Type","text/html;charset=utf-8");// If you do not set the encoding format and use Chinese, the code will be garbled res.end(" The request successfully returned data ") }) // Start the server serve.listen(8088,()=>{ console.log(" Server started successfully :http://127.0.0.1:8088"); })
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