14_ExpressJS.js

/*
https://expressjs.com/

->Express.js:
    -Used to create servers in nodejs very easily i.e creating APIs easily
    -It's is popular framework for building web applications and APIs using Node.js

  install express.js using this command: npm i express
*/

//importing express js
const express = require('express') 
//the blue print of express() is now inside 'app' its like instance of express
const app = express() //'app' can be any name but generally all developers use 'app'

/* ->app.get takes two parameters:
      (app.get() is a method in Express used to define a route that listens for GET requests on a specific URL or endpoint.)
      1)to which endpoint it needs to be shown  (kon se endpoint pei ye show hona chahiye) 
        here endpoint is "/", i.e after address when the user types this "/", the user will get data

      2)a callback function that handles the request and response (req, res)
          req->request
          res->response: what response you want to send here it's "Hello Express"

*/
//app.get(path, callback)
//localhost:3000 or localhost:3000/
app.get('/', (req, res) => {
  // res.send("hello express") //if you use this as well then only this will be shown in response of tha api, it will return first res.send
  res.send('Hello Welcome to my hotel!')
})

//another get request: localhost:3000/menu
app.get('/menu',(req,res)=>{
  res.send('We currently have: Pizza, Burger, Egg Roles, Briyani, Butter Chicken, Tandori Chicken')
})

//localhost:3000/sunday_special
app.get('/sunday_special',(req,res)=>{
  res.send('Sunday Special is: Chicken Pizza + 2 burgers @499 only')
})

//return object
app.get("/pizza",(req,res)=>{
  const pizzaInfo={
    name:"Chick Pizza",
    size:"large",
    cheeseTopping:true,
    extraCheese:false,
  }
  res.send(pizzaInfo) //o/p will be json string
})

app.get("/fridaySpecial",(req,res)=>{
  const biryani={
    name:"Wazwan biryani",
    size:"Large",
    price:699,
    extraRice:true,
  }
  res.send(biryani)
})


//3000 is port, telling that server is active on port 3000
// after running the code, go to web browser and type localhost:3000/
//app.listen(3000) 
//or
app.listen(3000,()=>{
  console.log("Server is listening on port 3000")
})

//you can also run this inside the postman : http://localhost:3000/ , http://localhost:3000/pizza , http://localhost:3000/menu

//sample POST Request
app.post('/order',(req,res)=>{
  res.send("Order Received!")
})
//Now it this endpoint : http://localhost:3000/order but with POST Request and for now send any json data or empty data
//it will give "Order Received!" as o/p in postman

//Note: To run this file do this in terminal: node --watch 14_ExpressJS.js (--watch is optional)