What is Express in Node.js?

September 8,2020 - 15 min read
Mean stack, Express in Node js

A fast, unopinionated and minimalist framework

Since the advent of Node JS in 2009 by Ryan Dahl, the creation of a server-side application in Javascript has become easy! For those who don’t know, Node.js is a cross-platform runtime environment for Javascript which let users build applications outside of browsers, on a desktop or any operating system. While Node JS is great at what it does, there are still a number of tasks that you can’t execute without external dependencies. In such situations, it’s best to take help. One such framework you would love to work with is Express.js.

Issues will crop up in an isolated Node.js application if you want to integrate specific handling for different HTTP requests or separately handle requests from different URL paths, create dynamic responses by using a template or serve static files. At this step, you either write the entire cumbersome code for yourself or use a framework that does the job for you without reinventing the wheel!

One such framework for Node.js in called Express.js. Initially developed by T.J. Holowaychuk, Express is a popular yet minimalistic framework you would love to use! It is written in Javascript and Node.js is its platform.

For geek nerds like you, it is not enough to just know a web framework like Express from the surface. Hence, a detailed analysis is assembled just for you, go and read on!

Understanding Express in Node.js

An elementary definition of Express is a ‘web framework for Node.js.’ While this definition encompasses the major functionalities of Express, it fails to capture the efficiency and excellence, Express in Node.js brings in a developer’s life.

A debugging mechanism, template engines, handling HTTP request and much more. Express encompasses in itself numerous features that aid developers. To get a hang of this amazing framework, it is essential to understand Express in Node JS a more detailed manner.

Fast, Unopinionated and Minimalist

According to the official website, Express is fast, unopinionated and minimalist. The framework delivers high performance and fast delivery. The framework has features of web applications but that doesn’t mean Node.js is neglected. Express makes sure the features you are already familiar with don’t get lost with the advent of new ones. Imagine Express as a layer of an additional and cool set of features built on top of Node.js.

Express follows the philosophy of 'Less is more.' The minimalistic nature is efficient yet beautiful because it doesn't come in the way of a developer's expression.

But other than being highly efficient, Express is unopinionated. It doesn’t come with a pre-defined set of rules which you have to follow. There are minimal restrictions; developers have the freedom to augment their possibilities and create codes using varied components together. Add middleware packages, structure the app into one or multiple files or use any directory structure. The point is that this is an unopinionated framework which sets you free. No stereotypes, expectations or judgements, at Express you express uninhibited!

More often than not, all other frameworks provide a robust set of features but are way too complicated for beginners. Even before the first line is coded, there is a plethora of functions that burden the developer unnecessarily. Express takes care of that. It is quite a flexible framework that allows developers to add what they want to only when they need to and not otherwise!

Single, Multiple and Hybrid Web Pages

This framework allows you to make single, multiple and hybrid web pages in a more efficient manner. Let’s understand this statement in a detailed manner. Express lets you develop single, multiple pages and also hybrid ones. This feature is more important and useful than it sounds. Here's how.

Single page web applications are relatively a new concept but prove to be very useful in the world of web. While surfing single page web applications, the entire or majority of it is accessed one single time. The evident advantage of the single-page web application is that navigation time is less and access is easy.

While single page web applications are quickly gaining popularity, one cannot neglect the prominence of multi-page web applications. Express gives a unique feature which lets you develop hybrid applications. It is a combination of single and multiple page web applications. In a hybrid version, developers can decide which content should be a single page app and which one should be accessed by individual requests. Express in Node.js provides a robust set of features which lets you develop hybrid applications which utilize both the approaches of single and by multiple web page applications.

The MEAN Stack

Often, Express in Node.js is used as a backend server in client-server architecture. It is a part of the MEAN stack. This stack consists of Angular for displaying the end result to the user (basically the front end), Mongo Db database for storing and retrieving data, Node.js for handling client and server requests and of course Express for making the request to the database and returning a response. In the first step, the client makes a request, which goes to the AngularJS, the request is then parsed by the Node JS server. Express.js makes a request to the database, which in this case is MongoDB. The database then returns the request. AngularJS displays the output as the final step. The entire MEAN stack is illustrated through the graphic.

Digging the Details of Express in Node.js

Coming to the technical part, Express provides a variety of features to help you in developing amazing mobile and web applications. The most distinguished one out of all is its ability to handle different HTTP requests (like POST, GET, DELETE) at different routes. Express in Node.js lets you define routes of your application based on specific HTTP methods and URLs. It basically provides an efficient routing mechanism for this purpose. Routing is simply the preservation of web page stats through their URLs. Node.js also has a routing mechanism but unlike in Express it is basic and rudimentary.

HTTP requests can also be used to create RESTful API services in Express. For the less nerdy ones, APIs are communication interfaces between two entities and one of the most popular APIs is REST. RESTful API services are HTTP protocols that leverage communication between client and server.

Express also comes up with a debugging mechanism, which is probably why Express is a popular choice among developers. A single bug can fail the entire code and cause the application to stop. Hours of hard work go to waste just because a single error decides to appear out of nowhere!

Express in Node.js has an efficient process to debug. It uses debug module internally to aid the process of developing codes.

Debugging is the most vital but frustrating task a developer has to go through. Fortunately, Express comes with an efficient debugging mechanism that makes it easier for developers by pinpointing the exact lines that may contain errors.

Express in Node.js also comes up with a template engine that makes applications more efficient. In simple language, a template engine lets you build static HTML pages but at runtime, it replaces variables with actual values. It builds HTML pages on the server-side so that the dynamic content gets the exact real value.

This feature makes the whole process of building web pages easy and efficient. There are a number of template engines that are compatible with Express including Pug, Dust and Mustache among others.

Code your Way up in Express in Node.js

Now that we have understood the importance of Express in Node.js in the world of web, let’s dive into some basic code which would help you start your own journey with this amazing framework called Express.

We will see how your favorite ‘Hello World’ program looks in Express.

Let’s get started!

To begin with, you need to first install Node.js and then Express if you already haven’t. Now, it is time we understand the code thereafter.

  1. var express = require(‘express’);
  2. var app = express ();

    These two lines import the express module and create an express application. We have named the object app here and it has all the robust features we talked about. Routing HTTP requests, registering template engine, rendering HTML pages and much more!

  3. app.get(‘/’, function(req,res){
  4. res.send(‘Hello World, I’m starting with express wish me luck’);}

    This piece of code is important for route definition. They define a callback function which will be called or revoked whenever there is an HTTP request. In this case, it is explicitly mentioned about the HTTP GET request. The function calls send () and would return ‘Hello World, I’m starting with express wish me luck’

  5. app.listen(3000,function() {
  6. console.log (‘My express app working fine! It’s listening on port 3000!);

    With this, a server is started at port 3000 and a comment is printed on the console log. If the server is running, you can go to localhost:3000 and see the output.

Congratulations! You have created your very first Express application! While this was a very basic piece of code, you have at least understood the robust architecture of Express.js and indulged in introductory coding involved with it.

The next obvious step would be creating a web page with dynamic content. All you need to is to take input from user and display the value at run time. Sit hot cup of coffee at hand, and dive deep in the world of Express in Node.js.

A Quick Summary

Express is definitely one of the most popular and efficient Node.js frameworks that allow server-side development using JavaScript. It enables developers to make highly scalable applications in less time! If you want excellence and efficiency in developing web projects, Express in Node.js is the right choice.

We discussed Express.js in a comprehensive and detailed manner. The features we covered are setting up middleware to respond to HTTP requests, rendering of dynamic HTML pages using template engines, debugging mechanism that makes that makes the whole process quick and efficient and other robust features.

Express is becoming immensely popular among developers, companies and technocrats. Companies like Twitter, STACK, Myntra, Bepro company are using Express in their technological stack and this majorly explains the reason behind the fame Express has managed to garner for itself.

We have tried to cover majority of features of Express in Node JS, but there might be some aspects that had been missed. Comment down and let us know about your experience with Express in Node.js that we did not talk about.

A Glance at the Future

Web development is one of the most thriving domains in the world of technology. Companies across the world are investing to make their online presence felt in the most creative of ways. Developers that have knowledge of the most advanced languages and frameworks are in most demand. If you know or are planning to learn the little nuances of Express in Node.js, you are definitely on track to build a successful career in technology for yourself.

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