Node-JS

Here we will be going to note down all node JS related Note what we are learning in my journey. For Start using node js Download it. Download recomended version.

Short Notes

require('fs') => use to import fs in current program
fs = require('fs') => for re use fs

Synchronous

If you use Synchronous way then , first Synchronous method will execute then the other part will execute``

fs.mkdirSync => crete directory
fs.writeFileSync => create and write in file
fs.appendFileSync => add text in next line or end of existing file
fs.readFileSync => for reading file (we get buffer data to get string use utf-8)
fs.renameSync => for renaming file
fs.rmdirSync => for removing directory
fs.unlinkSync => for removing or delete file

Asynchronous Way

fs.mkdir => crete directory
fs.writeFile => create and write in file
fs.appendFiel => add text in next line or end of existing file
fs.readFiel => for reading file (we get buffer data to get string use utf-8)
fs.rename => for renaming file
fs.rmdir => for removing directory
fs.unlink => for removing or delete file

Path Modules

path.dirname() => for getting file location
path.extname() => for getting file extention type
path.basename() => for getting file name
path.parse() => for getting all data about file in a object
parthParseObject.objectType => for getting data form object.

For more information click here

Import Export Module

module.exports={name of the functions} => You can export modules. You can export multiple funciton by separating , and here exports will be a object
const variable = require("path of the module") => By requiring you can use modules in desire file
const {name of the modules} = require("path of the modules) => Using this method you can access all the modules just by their name

Node module

Some importent notemodules

if you like to explore more module click here

Node Package Manager

npm init => to install npm use this command
npm install module_name or npm i module_name => use to install new module
npm install module_name@version => use to install with version

Http Server

First require http module (http)
createServer((req,res)=>{// Manage request}) use to create server
req.end() use to manage request
server.listen(port,"localhost",()=>{responserd}) user to listen server response , here in place of port you sould place a port number and in place of localhost place you need to place ip number normaly it is 127.0.0.1
localhost:yourport_number by using this url you can see your server routing pages
createServer((req,res)=>{}); here req.url lisent the url in server
res.end("content") is used to show content in webpage
res.writeHead(404,{"content-type":"text/html"}); is used to show status code of the page , also it shows the page type liek is it txt or html

JSON

JSON.stringify() => it is used to convert object to json
JSON.parse() => use to convert json to object
object[i].name => if you want to access a particular data from a simple object then you can use this eway(here i is index value)
object.name[i].id => if you want ot access data form a nested object then you can use this method (here i is index value)

Event Modules

Event module is basicaly is a Event handeling module which is use to handle events in your website

const EventModule = require('events') in this way we can import events module , you must be remember first it create a class
const event = new EventModule() in this way we need to make a object and using this object we can access all function of the module
event.emit("checkEvent") this is the way to create a event , also you must remember you need to add event name like checkEvent
event.on("checkEvent",()=>{// your resposend}) using this function we can handle event and in call back function we need to add responsed and you must remember This function should be placed before emit the event

Stream

stream = fs.createReadStream("data.txt") we can import stream function
stream.on("data",(chunkdata)=>{// code here}) to start stream on and it and to write data you should call data event
res.write(chunkdata) use to write data and here res is the response of the server
stream.on("end",()=>{res.end();}) this method is used to send responsed to the server
stream.pipe(res) => using this method you can send responsed data to the server and show it live

vagabon-09 / Node-JS