Our Top 10 JavaScript Libraries to Learn for 2019

Introduction

JavaScript has been around for a long time now and is backed by a huge community of developers. When these developers commit themselves to write brilliant open-sourced code, the result is user-friendly, useful and downright impressive javascript libraries that we can leverage into our projects for free.

While it’s hard to comprehend the exact monetary value of leveraging libraries within an application, it’s important to note the advantages of finding the right libraries for a new project. Whether you’re an employed developer or a freelancer, the right choice can save you a ton of time; And as we know, time is money. Out of the box, libraries provide a huge array of functionality that is usually tested, scrutinised and easy to leverage into an existing application.

Libraries vs Frameworks

Before we begin, it’s worth clearing the air about what constitutes a library, and what we should consider a framework.

In lamens terms, a library is a set of reusable functions used by an application. In contrast, a framework dictates the architecture of the application. For example, you may incorporate JQuery into your existing application to enhance functionality – but the same can’t be said for Vue.js or Angular.js. Simple right? Well… no. There are some technologies out there that blur the line between library and framework, making it difficult for developers like us to classify it; we’re looking at you React.

To save ourselves some confusion, and to give potentially lesser-known technologies a big shout-out, we’ll be steering clear of identity-confused technologies like React in this article.

1. RxJS

Functional reactive programming is a paradigm designed to deal with change and data streams within an application. ReactiveX is currently the frontrunner in the reactive library space, supporting a whole host of programming languages – including the JavaScript version RxJS. Simply put, RxJS is the combination of the observable and iterator design patterns to better allow handling asynchronous events.

If you’re new to reactive programming or RxJS, this post on GitHub Gist is a fantastic place to get started.

2. Redux

When writing modular front-end applications, handling state in a predictable and reliable manner can be tricky. Thankfully, this is where Redux steps in. Redux manages the state of an application based around the principle of a store. Application state is declared read-only within the store and mutations are made through the use of pure functions. With all this functionality wrapped up in just 2KB (including dependencies), there’s really no reason not to give it try.

3. Mocha

Test-driven development (TDD) is an approach to software development that places emphasis on writing clean, robust and less error-prone code. There are plenty of JavaScript testing libraries out there, but it’s Mocha that makes it onto our list.  Mocha is a simple, fun and flexible unit testing framework that works with both test-driven and behaviour-driven development. It doesn’t come with its own assertion and mocking libraries – so developers can decide which library they want to use.

Recently, we published an article regarding the importance of testing, as well as highlighting the potential earnings from becoming a test-driven developer.

4. Chart.js

There comes a time in every developer’s career when they have to visualise data in some user-friendly manner. Luckily for us, somebody has done all the hard work and allowed us to import their code as a library; Not all heroes wear capes. The internet holds plenty of JavaScript chart and graphics libraries, but one that stands out above the rest is Chart.js. It’s simple to use, looks visually stunning and is built on the HTML 5 canvas which offers great performance across browsers.

It’s also that worth noting that because of its popularity, you can probably find an official wrapper for the framework you’re building with. If you’re a fan of Vue.js the, you can get stuck into vue-chartjs. Otherwise, you can find react-chartjs and angular-chart.js over on GitHub.

5. Lodash

Lodash is seen by many as the JavaScript utility library and is the first port of call when setting up a new project. It’s full of useful helper methods that will have you screaming “Why isn’t this in vanilla JavaScript?” at your monitor.

Let’s take a quick look at some of the example methods that Lodash offers us.

Firstly, the flattenDeep method quickly flattens an n-dimension array into a simple one.

// Load the full build.
var _ = require('lodash');

_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

Next, let’s sneak a peek at one of Lodash’s string manipulation functions, reverse. As you may expect, this function takes a string, reverses it and returns the output.

// Load the full build.
var _ = require('lodash');

var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

The full list of functions is avaiable over in their docs.

With the core build weighing in at a minuscule 4KB, you’ll barely notice it’s there.

6. Math.js

As fun as it is to sit down and spend hours translating mathematics into code, it’s reassuring to know that Math.js is there to back us up. Math.js is an extensive mathematical library for JavaScript containing a huge array of functions and constants and is even compatible with JavaScript’s built-in Math library.

7. D3

Earlier, we mentioned chart.js – a beautiful chart library for JavaScript. While chart.js provides a handful of useful charts that will often provide the functionality we need, it is by no means a comprehensive data visualisation library; This is where D3 steps in. D3 is an abbreviation for data-driven documents and helps developers bring data to life through modern front-end technologies.

In a few words, it works by binding data to the Document Object Model (DOM) and applying data-driven transformations to the document. If you’re still not excited by the endless possibilities, head over to the D3 homepage and check out the huge hexagonal array of examples.

8. Jest

We’re back to testing libraries, and next up is Jest. Jest is an open-sourced JavaScript testing framework developed and used by Facebook and is baked into React’s create-react-app command.

Unlike Mocha, which we previously listed, Jest comes with built-in assertion and mocking functionality. In addition, Jest offers Snapshot testing functionality which renders UI components and compares the component to a reference image stored for the test.

9. GSAP

GreenSock’s GSAP was designed to be the standard for JavaScript HTML 5 animations. It boasts crazy performance, freakish robustness and compatibility with most front-end technologies and internet browsers all the way back to IE 6. GSAP’s flexible, modular structure has been built without the use of dependencies to keep the library as performant as possible.

GSAP’s example showcase page pays homage to what is achievable with this library.

10. SocketIO

SocketIO is the library for creating real-time web applications. It focuses on enabling real-time, bidirectional and event-based communication designed to work on every browser, platform and device. The library is split into two parts that you’ll need to implement to get started – a client part which runs in the browser and a node.js server part which the client connects to.

You can head over to socket.io to dive into an amazing introduction to how this library works.

Wrap up

In this article, we’ve discussed our top 10 Javascript libraries to learn for 2019.

Whether it’s testing, visualising data, creating a real-time chat app or building animations – there’s a library out there to suit our needs.

 

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