• Create a new folder and call it hello_world.

 mkdir hello_world
 cd hello_world

1. In your hello_world folder create a new file called app.js

 touch app.js

1. Note: you can install node here and

   1. then run cmd with npm init ()

   2. press enter for continue.

   3. enter cmd with npm install express --save

1. Add content to file app.js

2.    //Require module
      const express = require('express');
      // Express Initialize
      const app = express();
      const port = 8000;
      app.listen(port,()=> {
      console.log('listen port 8000');
      })
   
      //create api
      app.get('/hello_world', (req,res)=>{
      res.send('Hello World');
      })
   

Test: with browser: http://localhost:8000/hello_world

Check postman

input: http://localhost:3000/hello_world and then click The send button