Node js

 const file = require('fs');

const result = file.writeFileSync("hello.txt", "Hello my name is aditya");

console.log(result);

//hello.js

console.log("hello");

const math = require("./math");

//console.log(math.add(3,5));

const value =math.add(3,5);

console.log(value);

//maths export

function add(a , b){

  return a + b;

}

function sub(a,b ){

  return a-b;

}

//we have to export functions to use them in other files because we run the server with only one file

module.exports = {add,sub};

//server.js

const http = require("http");

const fs = require('fs');

const myserver = http.createServer((req, res)=>{

const log = `${Date.now()} : ${req.url} :The request recieved\n`;

fs.appendFile('serverlog.txt', log, (req, res)=>{ })

  // console.log("request recieved");

  switch(req.url){

    case "./":

      res.write('this is home page');

      break;

    case "/about":

      res.write("This is about page");

      break;

    case "/contact":

      res.write("this is contact page");

      break;

  }

  // res.end("   hello everyone  ");

});

myserver.listen(9000, ()=>{

  console.log("server has started at port 9000");

})

//project 01

  const express = require('express');

  const app = express();

  const users = require('./mock-data.json');

  const port = 3000;

  app.use(express.json()); // For parsing application/json

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

  app.get('/users', (req,res)=>{

      return res.json(users);

  })

  app.get('/users/:id', (req,res)=>{

   const id = Number(req.params.id);

    const user = users.find(user => user.id === id);

    return res.json(user);

  })

  app.route('/users/:id').patch((req, res) => {

    //update the user data with given id

    return res.json({messge: "The id is being updated"});

  }).delete((req, res) => {

    //delete the user data with given id

    return res.json({messge: "The id is being deleted"});

  }).post((req,res)=>{

    return res.send("The post request is in pending");

    const newdata = req.body;

    console.log(newdata);

    return res.send("wait");

    // users.push({...body, body:id= users.length+1 })

  }

  )

  app.listen(port, () => {

    console.log(`Server is running on http://localhost:${port}`);

  });