Best JavaScript Frameworks, Libraries and Tools to Use in 2019

It seems there are more JavaScript frameworks, libraries, and tools than there are developers. As of May 2017, a quick search on GitHub reveals more than 1.1 million JavaScript projects. There are 500 thousand usable packages on npmjs.org with almost 10 billion downloads every month.

This article endeavors to explain the basics and rudimentary differences between the most popular client-side JavaScript frameworks, libraries, and tools. Whether they are "best" for you is another question. Choose something and stick with it for a while. Just be aware your favorite option will be superseded by something "better" no matter what you select!

Please accept the following terms and conditions before reading this article...!

• The JavaScript landscape changes on a daily basis. This article will be out of date the moment it's published!
• By "best" I mean "the most popular general-purpose projects". All are free/open source but the list may not include your favorites.
• Discontinued projects such as YUI are not included even though they may still have high use across the web.
• Only client-side projects are referenced. Some can work server-side but the list does not include pure server-based frameworks such as Express.js or Hapi.
• Information about each project is intentionally brief to provide an overview for further research.
• Each project provides a usage popularity indicator but statistics are notoriously difficult to collate and can be misleading.
• I'm biased. You're biased. Everyone else is biased! I haven't tried every tool here and will declare my favorites but you should make your own assessment based on your requirements.
• Neither I nor SitePoint are liable for any disastrous decisions you make!

Tricky Terminology

The terms "framework", "library" and "tool" can mean different things to different people at different times depending on the context. The general definitions used here:

Libraries

A library is an organized collection of useful functionality. A typical library could include functions to handle strings, dates, HTML DOM elements, events, cookies, animations, network requests, and more. Each function returns values to the calling application which can be implemented however you choose. Think of it like a selection of car components: you're free to use any to help construct a working vehicle but you must build the engine yourself.

Libraries normally provide a higher level of abstraction which smooths over implementation details and inconsistencies. For example, Ajax normally relies on the XMLHttpRequest API but this requires several lines of code and there are subtle differences across browsers. A library may provide a simpler ajax() function so you're free to concentrate on higher-level business logic.

A library could cut development time by 20% because you don't have to worry about the finer details. The downsides:

• a bug within a library can be difficult to locate and fix
• there's no guarantee the development team will release a patch quickly
• a patch could change the API and incur significant changes to your code.

Frameworks

A framework is an application skeleton. It requires you to approach software design in a specific way and insert your own logic at certain points. Functionality such as events, storage, and data binding are normally provided for you. Using the car analogy, a framework provides a working chassis, body, and engine. You can add, remove or tinker with some components presuming the vehicle remains operational.

A framework normally provides a higher level of abstraction than a library and will help you rapidly build the first 80% of your project. The downsides:

• the last 20% can be tough going if your application moves beyond the confines of the framework
• framework updates can be difficult - if not impossible
• core framework code and concepts rarely age well. Developers will always discover a better way to do the same thing.

Tools

A tool aids development but is not an integral part of your project. Tools include build systems, compilers, transpilers, code minifiers, image compressors, deployment mechanisms and more.

Tools should provide an easier development process. For example, many coders prefer Sass to CSS because it provides code separation, nesting, render-time variables, loops, and functions. Browsers do not understand Sass/SCSS syntax so the code must be compiled to CSS using an appropriate tool before testing and deployment.

Don't Label Me!

The distinction between libraries, frameworks, and tools is rarely clear. A framework could include a library. A library may implement framework-like methods. Tools could be essential for either. I've attempted to label each project but the scope can vary.

If this sounds too complicated, you could consider coding vanilla JavaScript. That's fine, but you will inevitably write your own library and/or framework code which must be maintained. JavaScript itself is an abstraction on a tower of browser and OS abstractions!

JavaScript Frameworks and Libraries

Projects in order of popularity...

jQuery

jQuery
type	library
website	jquery.com
repository	github.com/jquery/jquery
current version	3.2.1
developer	jQuery team
launch date	August 2006
typical size	30kb min
typical use	general purpose
usage	72.4% of all websites

jQuery remains the most-used JavaScript library ever created and is distributed with WordPress, ASP.NET and several other frameworks. It revolutionized client-side development by introducing CSS selector to DOM node retrieval plus chaining to apply event handlers, animations, and Ajax calls.

jQuery has fallen from favor in recent years but remains a viable option for projects which require a sprinkling of JavaScript functionality.

Pros:

• small distribution size
• shallow learning curve, considerable online help
• concise syntax
• easy to extend

Cons:

• adds a speed overhead to native APIs
• less essential now that browser compatibility has improved
• usage has flat-lined
• some industry backlash against unnecessary use.

React

React
type	library
website	facebook.github.io/react/
repository	github.com/facebook/react
current version	15.5.4
developer	Facebook and contributors
launch date	March 2013
typical size	21kb min
typical use	single-page applications
usage	low

Perhaps the most-talked about library of the past year, React claims to be a JavaScript library for building user interfaces. It focuses on the "View" part of Model-View-Controller (MVC) development and makes it easy to create UI components which retain state. It was one of the first libraries to implement a virtual DOM; the in-memory structure computes the differences and updates the page efficiently.

React usage appears low in statistics perhaps because it's used in applications rather than websites. Almost 38% of developers claim to be using the library.

Pros:

• small, efficient, fast and flexible
• simple component model
• good documentation and online resources
• server-side rendering is possible
• currently popular and experiencing rapid growth

Cons:

• new concepts and syntaxes to learn
• build tools are essential
• can require other libraries or frameworks to provide the model and controller aspects
• can be incompatible with code and other libraries which modify the DOM

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