ExpressJS

What is ExpressJS?

Express.js is a Node.js web application framework that provides features for building web and mobile applications. It is one of the most popular frameworks for Node.js due to its simplicity, ease of use, and extensive ecosystem of middleware.

Why ExpressJS?

• Minimal: Express is a minimalistic framework that does not impose any structure or methodology on applications, giving developers the flexibility to structure their apps as they wish.
• Middleware: Middleware functions have access to the request object (req), the response object (res), and the next middleware function in the application’s request-response cycle. ExpressJS can perform a variety of tasks such as executing code and making changes to the request and response objects, with the help of middleware.
• Routing: Express provides a routing mechanism to handle routes for our application and specify how the application responds to client requests.
• Extensible: Express is highly extensible through a wide variety of middleware modules available on npm. This makes it easy to add functionality to our application, such as logging, authentication, and database interaction.

Setting up an ExpressJS Project

• Since I already have Node.js installed, we start with creating a new project directory.
• Run npm init to create a package.json file.

npm init -y        

This creates our project.

• Install Express using npm.

npm install express        

This installs Express as our dependency for our project.

• Create a server.js file and set up the Express server as below.

const express = require('express')
require('dotenv').config()
const app = express();  
 
const port = process.env.PORT || 8000;

app.use("/", (req, res)=>{
    res.json({
        name:"Aastha",
        age:"19",
        profession:"Student",
        address:{
            temporary_address:"Kathmandu",
            permanent_address:"Jhapa"
        },
        message:"This server is developed by Aastha"});
})

app.listen(port, () => {
    console.log(`Server started on ${port}`);
})        

• For .env file, we install dotenv as another project dependency.

npm i dotenv        

Once installed, we create a .env file which stores our environment variable. In this case,

PORT=5000        

• Run the server.

node server.js        

Thanks to our mentor, Bikash Karki , for his insightful lecture.