What is Node JS and What Is It Used For?

JavaScript is the most popular client-side programming language supported by most modern browsers. It’s responsible for adding interactivity to web pages by responding to user actions (events) such as clicks, scrolling, and form submissions. Using it, developers also create animations, do input validation, update UI, etc.

Before 2009, JavaScript was only used in client-side scripting, and the idea of it being used on the server was considered fiction until an American software engineer, Ryan Dahl, created Node.js. With it, big companies like Netflix, Paypal, Uber, IBM, Twitter, and others use JavaScript within Node.js on the backend for their web apps, cloud streaming solutions, and microservices. Some — like NASA — utilize Node.js for their Mission Control Center: the tool provides real-time data for their space missions.

But what is Node.JS? How does it work? How did this tool change the approach to development once and for all?

What’s Node.JS? What makes its architecture special?

One of the most popular and wrong thoughts about Node JS is that it’s a JavaScript framework. Actually, it’s an open-source JavaScript runtime that was developed with C/C++ built on Chrome's V8 JavaScript engine. In other words, unlike frameworks, Node.js provides an environment for executing commands, but it isn’t opinionated and doesn’t enforce patterns on how to write code. So, with Node.js on the backend, and JavaScript — on the front end, development is much faster and simpler because of the shared language. Within that space, it’s easy to share and reuse code and keep back- and front-end synched.   

Node.js has a large ecosystem of libraries and frameworks, APIs, and modules for file systems, networking, and other functions. Its large, growing community of developers produces a lot of documents, guides, and instructions for various projects. That simplifies development a lot, too.  

But Node.js's main benefit is its architecture — or, more accurately, the way it handles client-server interactions. Node.js is commonly used for building real-time, high-performance, and scalable network applications. Let’s break down the way it handles requests and responses first. 

Requests and responses are part of the client-server relationship. A request is an action or event performed by the client, such as sending an HTTP request to the server. The response is the web server’s reply to the client’s request. The web server listens to the client request through the event listener, processes it, and then responds appropriately. For example, if a client sends an HTTP GET request to get specific data from a server, the web server will receive this request, process it and respond with the requested data.

Node.JS can handle multiple requests in parallel, without waiting for each request to complete before processing the next one, so all executions become non-blocking. It does so through two techniques: using non-blocking input/output and callbacks/promises. 

Non-blocking Input/Output Model

Before Node.JS, it was common that, within a single thread, the program stops execution waiting for the I/O process to complete. In other words, it waits until the command or function gets data from the server before starting to process the next request. (Alternatively, if the language supports multithreading, the program creates a new thread to process the new request, — but, while viable, it puts pressure on the RAM and can slow the program down, especially if we’re talking about apps that handle real-time data flows.) 

Node.js uses a non-blocking I/O model that allows processing new requests without the wait time in an asynchronous way. Within a single thread, programs start processing a new request while other requests keep running in the background. 

CallBack Functions and Promises

A callback is a function that “activates” after a certain result connected to it is achieved (e.g., another function has been executed). In the past, nesting several callbacks inside a function has been the most common way of achieving asynchronous operations in JavaScript, but it led to callback hell — issues with timely execution and bad code readability within nested callbacks. 

To resolve this issue, but maintain asynchronous operations, Node.js came up with promises. Promises are functions that “promise” to a callback request the value it cannot return right now — and this request goes into the background while other requests are being processed. A callback function reacts to a promise when it’s fulfilled or rejected, sends it to the event loop, and forms an answer to a request. In such a way, if some I/O tasks need to be processed longer than others, they don’t pile up in the queue, creating delays, but stay in the thread pull until called upon after fulfilling the promise without overwhelming the system.  

So, because of these functions, Node.js is capable of running asynchronous operations efficiently — without delays and putting a lot of pressure on the system. 

Node.JS: where is it worth using?

Now that we’ve figured out what makes Node.js special, let’s review the most common use cases in which it’s used. 

Real-Time Lightweight Apps

Node.JS can handle many simultaneous connections efficiently, so it’s well-suited for real-time apps like:

• Chat applications & social media: Node.js has a lot of built-in features for creating real-time chats and chatbots, (Express.js framework is great for creating those, along with API tools for connecting to many 3rd-party services) and is capable of gracefully handling concurrent updates from multiple users. There are a lot of big communication platforms using Node.js, e.g. Slack and LinkedIn (which switched to Node.js from Ruby on Rails and managed to make the app run 20 times faster.) 
• Online games: similarly, online games are another perfect case for using Node.js — in particular, HTML5+ games. Game developers use JS-based game engines like Phaser with Node.js back-end server and can create games that are fast, have well-performing multiplayer, and maintain high performance in any browser, web, or mobile.
• Features for analytics: Node.JS is commonly used in building real-time analytics systems, as it provides packages and frameworks that allow servers to handle vast amounts of incoming data and process it without being heavy on CPU. E-commerce solutions are the ones who often take advantage of that — and IoT apps, but we’ll talk about them later.
• Collaborative applications: Node.js is also used for building collaborative tools many people will use simultaneously, e.g. Trello and Slack. 

Multimedia Streaming Apps

Node.js is well-suited for building streaming applications, such as video streaming, audio streaming, and live broadcasting platforms. 

Besides the fact it provides a way to handle many users and large amounts of data in real-time, it opens a connection between real-time data from the streaming app and the local system, which makes it a good alternative for caching and temporary storage. As there is no need for caching and temporary storage, we can process data while it is still being uploaded, cutting on the wait time. 

These features are a major reason why apps like Netflix are utilizing Node.js. Because Netflix wants the best experience for their millions of users, the videos on their website & app need to be downloaded fast & in high quality. Also, Node.js allows them to easily maintain and observe the performance of the app (see: analytics capabilities), which is important for their content KPI analysis. 

Internet of Things (IoT)

There are different reasons why Node.JS is perfect for building IoT apps, including:

• Using JavaScript in programming the front end makes using Node.JS the best choice in developing the backend to unify the ecosystem and enhance collaboration between the client side and the server side. That is vital for IoT infrastructure to be maintainable.
• Node.js, as we’ve mentioned, can process a lot of data in real-time streams — and it does so while not requiring a lot of processing power & memory, which is also important for IoT because the system must be lightweight.
• Node.js has a large ecosystem of packages, which allows developers to connect IoT devices to other systems, such as databases, cloud services, APIs, and so on. Case in point: NPM package contains lots of modules for IoT that help connect the software to Intel Edison, Raspberry Pi, and many popular Bluetooth modules and sensors.  
• It’s very compatible with JSON, a format that helps exchange data across the network quickly and, again, without putting a lot of pressure on it. 

All of these factors contribute to the fact Node.js is great for IoT. Apart from being great at handling data-intensive operations, Node.js is also simplistic and easy to work with in comparison with low-level languages like C++, in which codes for many IoT devices are done in. So, with Node.js building IoT infrastructure is fast as well. 

Other solutions with multiple API connections & microservices

Right now, a lot of apps on the web use multiple APIs for third-party services: to connect to payment gateways, AI algorithms, social media, and so on. For API connections to be stable and run without disruption, businesses need a backend tool that is capable of keeping them as such. Node.js is such a tool. 

Due to its architecture, Node.js is also a perfect backend tool for microservice architecture — or for solutions that plan to adopt it (like legacy systems that desperately need modernization), because various modules within it are often “talking” with each other via HTTP resource APIs. 

Creating a Bot for Slack using Node.JS - Twinslash Case

One of the cases involving Node.js our team has worked with was the development of an operation tracker bot for Slack. The idea was that people (especially managers) could send a bot a request for figuring out the status of certain tasks and, depending on what status was chosen by people who are assigned to these tasks, the bot would give out a response with parameters, like “we started”, “just about to finish”, “finished”, and so on. 

We utilized both Node.js and AWS Lambda; the latter is an event-driven compute service for running apps on the backend without dealing with server management. The bot was helpful for project management — it was possible to get updates about certain tasks without interrupting the team’s process and quickly see if someone has stuck and needed help. 

What Makes Node.JS Unique?

Let’s summarise what makes Node.js a good technology for the backend of your projects. It is:

1. A perfect fit with JS-based front-end tools. Projects using JavaScript on the client side and Node.js on the server will get all the advantages of full-stack JavaScript development, including a unified coding ecosystem, a simplified and more affordable talent hunt, and easier communication between engineers.
2. Scalable: It allows applications to be easily scalable as it can handle multiple concurrent tasks with high throughput due to non-blocking I/O and callbacks and promises. That means, Node.js software and apps will be able to handle growth gracefully, even if that means larger incoming streams of real-time data.
3. Well-performing: Asynchronous operations and the way they are presented in Node.js architecture allow Node.js apps to handle multiple simultaneous processes without losing high performance.
4. Compatible with many helpful packages: Node.js packages, APIs, and libraries will help you build the app even faster. 

On the other hand, Node.JS has disadvantages that make it not the best choice in some applications: it doesn’t handle CPU-bound tasks well, isn’t suitable for heavy computations, doesn’t have a lot of built-in out-of-the-box tools (because, you know, it is a runtime, not a full-blown library). So: pick Node.js if you want to handle a lot of data streams but not, like, build neural networks around those streams. 

Node.JS changed the way people build asynchronous operations on the backend — and its expanded JavaScript reach into the back end, which helped many companies and engineers. If you want us to help build a backend for your project using Node.js, don’t hesitate to ping us.