What is Express JS, and its Example

What is Express JS

•  Express JS is a NodeJS framework. It's the most popular framework as of now ( the most starred on NPM).

• Express JS is a web application framework that provides you with a simple API to build website, web apps and backends.

Why do we actually need Express JS ? How it is useful for us to use with Node.js?

• Try to write a small REST API server in plain Node.js (that is, using only core modules) and then in Express JS. The latter will take you 5-10x less time and lines of code.

get	Read API data
post	Create API Data
put	Update
delete	Delete Api data

Syntax

app.get(route, callback)

app.get("/", (req, res)=>{
})

• The Callback function has 2 parameters, request(req) and response(res).
• The request object (res) represents the HTTP  request and has properties for the request query string, parameters, body, HTTP headers, etc.
• Similarly, The response object represent the HTTP response that the Express app sends when it receives an HTTP request.

const express = require("express");
// const { route } = require("express/lib/application");
const app = express();
app.get("/", (req, res)=>{
    res.send("hello Alians");
});
app.listen(8000, ()=>{
    console.log("listening....");
});

 

  Express JS routing

const express = require("express");
// const { route } = require("express/lib/application");
const app = express();
app.get("/", (req, res)=>{
    res.send("hello Alians");
});
app.get("/about", (req, res)=>{
    res.send("hello Alians, this is about page");
});
app.get("/contact", (req, res)=>{
    res.send("hello Alians, this is contact page");
});
app.listen(8000, ()=>{
    console.log("listening....");
});