What is Node.js?

Node.js is a JavaScript runtime, which means it runs programs written in JavaScript. Most developers use it to create command-line tools or web server applications.

Node.js was initially developed by Ryan Dahl. He took the V8 JavaScript engine from Google’s Chrome browser, added some APIs, wrapped it in an event loop, and launched it as an open-source product on Linux and macOS in 2009. The Windows edition arrived in 2011.

The Node Package Manager (npm) was introduced in 2010. It allowed developers to use code modules published by others in their own projects. There was no official ECMAScript module standard at the time, so Node.js and npm adopted CommonJS.

The first (non-beta) release of Node.js arrived in 2015, with updates promised every six months.

Node.js wasn’t the first JavaScript runtime, but unlike other options—such as Rhino and SpiderMonkey —its popularity grew exponentially. Even those writing PHP, Python, Ruby or other languages often use Node.js tools to supplement their development processes.

Why Learn Node.js?

JavaScript is hugely popular on GitHub, and it’s ranked highly by developers. Companies including Netflix, Uber, Trello, PayPal, LinkedIn, eBay, NASA and Medium have adopted Node.js, and most professional developers will have encountered Node.js tools.

Below, we’ll look at some of the reasons you should consider using Node.js.

It’s JavaScript

JavaScript is used on trillions of web pages, where it has a browser monopoly. Every professional web developer requires JavaScript knowledge to program client-side applications.

Server-side languages are more diverse. Historically, developers could opt for PHP, Ruby, Python, C# (ASP.NET), Perl, or Java, but these have different syntaxes and concepts. It can be difficult to switch contexts, so larger project teams often split into frontend and backend developers.

Node.js allows a developer with frontend JavaScript knowledge to leverage their skills on the backend. It won’t make you a full-stack developer overnight, but the concepts are similar, and there’s less rigmarole when formatting JSON, handling character sets, using WebSockets, and so on.

It’s Fast

Most server-side languages are fast enough, but few match the speed of Node.js. The V8 engine is quick, and it evolves rapidly, having the weight of Google and Chrome behind its development. Node.js also has a non-blocking, event-driven I/O.

Let’s go through that again with less jargon. Most languages use synchronous blocking execution. When you issue a command—such as fetching information from a database—that command will halt further processing and complete before the runtime progresses to the next statement. To ensure that multiple users can have access at the same time, web servers such as Apache create a new processing thread for every request. This is an expensive operation, and Apache has a default limit of 150 concurrent connections. Busy servers can become overloaded.

Node.js code (and browser JavaScript) runs on a single processing thread. Long-running tasks such as a database query are processed asynchronously, which doesn’t halt execution. The task runs in the background, and Node.js continues to the next command. When the task is complete, the returned data is passed to a callback function. A Node.js program can have many hundreds of ongoing operations that are completed whenever they’re finished, meaning that the processor is free to tackle other tasks.

Asynchronous programming has challenges, but it’s possible to create fast Node.js applications that scale well.

It’s Real-time

Web platform features such as WebSockets and server-sent events permit real-time functionality—such as instant data updates, live chat, multiplayer games, and more. These can be difficult to implement in traditional server-side languages, where they often require third-party services. Real-time functionality in Node.js is significantly easier.

It’s Lightweight

The Node.js runtime is small and cross-platform. As well as catering for Linux, macOS, and Windows, you find editions for embedded systems, the Raspberry Pi, and even SpaceX rockets.

It’s Modular

Node offers a minimal standard library with good documentation. It contains basic functions for error handling, file system access, network operations, and logging.

For everything else …

It’s Extendible

Node.js has the largest package registry in the world, with more than one million modules. You’ll find pre-written code for task runners, loggers, database connectors, image processors, code compilers, web servers, API managers, and even client-side libraries.

The npm command-line tool is provided with Node.js and makes it easy to install, update, and remove modules. You can also use it to install global modules so Node.js scripts can run as commands from anywhere on your system.

It’s Open Source

Node.js is an open-source project. The runtime is free to use without any commercial restrictions. The majority of modules are also free, because they’re submitted by the community for the benefit of other developers.

It’s Everywhere

This course concentrates on web applications, but you can use Node.js to create serverless functions, deployment scripts, cross-platform command-line tools, and even complex graphical apps such as VS Code, Slack, and Skype—all of which use the Electron framework.

As a web developer, you’ll almost certainly encounter Node.js, even if it’s not a core part of your technology stack. Knowing a little Node.js could help your projects and career. You’ll have a better insight into the possibilities available to modern web applications.

Summary

In this chapter, you’ve learned that Node.js is a popular JavaScript runtime that’s uniquely suited to web development. I’ve summarized it in this chapter’s video. Chapter 2 describes how to install Node.js on your platform of choice.

Quiz

Many chapters in this course end with a quick quiz to ensure you’ve grasped the concepts. Beware! Some questions are designed to catch you out, so make sure you’ve been paying attention!