I wrote this article as a result of a discussion (I won't call it an argument because it occurred in a learning platform and we're all learning) - React is a Library, or React is a framework. I've been working with React for quite sometime and all the Devs I've worked with usually just call it a framework. And personally, I see it as a framework myself. I was surprised to see some folks saying that's wrong and it's just a Library. This article I believe should do a bit of expo to that, and if you have any reservation, feel free to comment.

In the world of JavaScript, one debate that continues to persist is whether React is a library or a framework. Officially, React is described by its creators at Facebook (now Meta) as a "JavaScript library for building user interfaces." However, if you've heard someone call it a framework, they aren't necessarily wrong. In this article, we’ll break down the reasons why React can be seen as both a library and a framework, and clarify the difference between a JavaScript library and a JavaScript framework.

What is a JavaScript Library?

A JavaScript library is a collection of pre-written JavaScript code that helps developers solve common problems and build features more easily. A library provides tools to perform specific tasks, but it leaves the developer in control of the application’s structure and architecture.

For example:

• React is often referred to as a UI library because it allows developers to build reusable UI components without dictating how the rest of the application should be built.
• Lodash is a popular JavaScript utility library that provides functions for tasks like working with arrays, objects, and strings. Lodash doesn’t dictate how your project should be structured; it just provides tools you can use where necessary.

In a library, the developer calls the library. This means the developer decides when and where to use the library's functions.

What is a JavaScript Framework?

A JavaScript framework, on the other hand, is a full-fledged toolset that dictates much more about how you should build your application. Frameworks provide a structured and opinionated approach to development, offering a complete solution for building applications.

In a framework, the framework calls the developer’s code, not the other way around. This distinction is referred to as "inversion of control." Frameworks provide default configurations, and the developer fills in the gaps by writing specific logic where needed.

For example:

• Angular is a framework that enforces a particular structure and pattern, such as using components, services, and a module system.
• Vue.js, although lighter and more flexible, still qualifies as a framework because it provides an end-to-end solution for building user interfaces and applications.

Frameworks are often seen as being "opinionated" because they come with rules about how you should structure your code, enforce patterns, and offer tools to handle routing, state management, and more.

Why React is a Library

React is officially described as a library because:

• It is focused on one specific task: building user interfaces.
• React does not impose a specific structure or architecture on your application. You can use React as little or as much as you need without adopting an entire ecosystem or specific conventions.
• Unlike frameworks like Angular or Vue, React doesn’t come with built-in tools for routing, state management, or making HTTP requests. Developers can add these features by using additional libraries (like React Router for routing or Redux for state management).

Essentially, React provides components and a way to render them efficiently. It doesn’t care how the rest of your application is organized, making it more flexible and modular than a traditional framework.

Why React is also a Framework

While React is a library at its core, calling it a framework is not entirely wrong either. Here’s why:

React Ecosystem:

• In practice, many developers use React alongside additional libraries and tools to build full applications, including React Router (for navigation), Redux (for state management), and Next.js (for server-side rendering). These tools combined create a full-fledged development experience, much like a traditional framework.
• The React ecosystem has grown to the point where you can build entire applications using only React-centric tools. Once you're immersed in the React way of doing things, it can feel just like using a framework.

Inversion of Control:

• While React doesn’t force you into a particular architecture, it does take control over rendering the UI and managing component states. This "inversion of control" characteristic is a hallmark of frameworks.
• React components dictate when they render and how their states change over time. The React lifecycle methods, hooks like useEffect, and the virtual DOM management are part of how React controls parts of your application.

Developer Experience:

• The fact that React often requires the use of a set of libraries (often React-specific) to build a complete application puts it in a similar category as a framework. When most developers think about using React, they are thinking not just about the core library but about the surrounding ecosystem of tools.
• Popular frameworks like Next.js, which is built on top of React, offer an all-encompassing structure that feels very framework-like, giving developers routing, server-side rendering, and static site generation—all using React.

Community and Conventions:

• Over the years, the React community has developed conventions and best practices around React development, such as the use of hooks, JSX, and component-based architecture. These conventions help streamline development and make React behave like a framework by providing guidance on how applications should be structured.

Full Application Development:

• With the introduction of tools like React Native (for mobile apps) and Next.js (for server-side rendered React apps), React has evolved beyond just a UI library. These tools allow developers to build full applications across different platforms, which aligns more with what frameworks traditionally offer.

Library vs. Framework: A Grey Area

The line between library and framework isn’t always clear. As we’ve seen with React, a tool can exhibit characteristics of both depending on how it's used. This grey area is common in modern JavaScript development, where the ecosystem is modular, and tools can grow beyond their original purposes.

• React, as a core tool, is a library that focuses on UI.
• However, the ecosystem around React and its conventions provide the framework-like structure for building full applications.
• When someone calls React a framework, they’re acknowledging the broad scope and ecosystem React offers, which resembles the capabilities of a framework.

Final Thoughts

Whether you call React a library or a framework depends largely on how you use it and the surrounding tools. What’s most important is recognizing that React can scale from a lightweight, flexible UI library to a powerful tool that acts as a framework in real-world applications.

So next time someone tells you React is "just a library," feel free to point out that it might just be a framework, too—depending on how you look at it.