React vs. Angular: What’s the difference and which should you choose?

React and Angular are two of the most popular tools used in modern JavaScript frontend development. They provide pre-built frontend functionality and a framework that you can incorporate into your projects, saving you from writing all of your code from scratch. While React and Angular share a lot in common, they have different purposes, which can lead to confusion when deciding which to use.

This article explains the difference between React and Angular and how they fit into a component-based application architecture, and includes real-world advice to help you decide which one you should choose if you are learning or starting a new project.

What is React?

React (also known as React.js and ReactJS) is a JavaScript library for building user interfaces for your websites and app front ends. It is developed by Facebook, which has made it open source and 100% free to use in your projects.

React is used to add interactivity to your pages and to provide reusable components: you can read and modify the HTML DOM (that's the hierarchy of HTML elements that make up your web pages) to dynamically change how the page looks and behaves without reloading it, and encapsulate the HTML, JavaScript, and CSS for an entire visual component so that it can be used multiple times without having to repeat any code (keeping it DRY).

React can be used to develop single-page applications for websites, and is also used to develop the user interfaces for mobile applications. You can use either JavaScript or TypeScript to develop React apps.

Notable projects that use React to build user interfaces include Facebook (of course), Netflix, Discord, Shopify, and Microsoft (where it’s used to develop the mobile versions of the Office and Outlook apps). We'll examine how React (and Angular) can be used to develop mobile apps later in this article.

Advantages of React

• Small bundle size and fast performance: React, not being a full framework, is much smaller than Angular, so it downloads faster and has less performance overhead.

• One-way data binding and a simple architecture: One-way data binding means that the user interface only reads data for display (so you have to take purposeful action to run a function to update data), making it more predictable and easier to debug. This is in contrast to Angular, which has two-way data binding, where the view and data model are automatically kept in sync (for example, multiple form inputs bound to the same variable would all update to the same value if one is changed). Which is best depends on your use case and personal preference, but many developers prefer React's simplicity in this regard.

• Integrate React with your existing pages: You can add React to existing projects and start moving your codebase to a component-based architecture without having to start from scratch.

What is Angular?

Angular (note, Angular is not AngularJS) is not just a library; it’s a full framework that uses the TypeScript language.

In addition to letting you interact with the DOM to add interactivity and build using reusable components, it includes everything else you need to build a full application, including client-side routing (so you can navigate between pages of your application using URLs), maintaining an application state (including keeping data in sync across application components), loading data from your backends, and interacting with native features of the browser it is running in.

Angular is developed by Google, and is also open source and free to use in your projects. Popular products built on Angular include Gmail, Upwork, PayPal, YouTube, and Weather.com.

Like React, Angular is used to develop single-page applications and mobile apps. As it does more than just provide a library for building user interfaces, it is quite opinionated about how its code is structured, so you cannot retrofit your old pages to implement Angular — your whole project has to be built using Angular, and it has to do things the Angular way. This isn't a problem for new projects, but can make it difficult to move existing ones to use the framework.

Advantages of Angular

• It includes the kitchen sink: Angular lets you build interactive user interfaces just like React, and also includes the tools to build the rest of your app, including loading data from APIs via HTTP, support for observables so that you can cleanly handle asynchronous tasks, routing to split your app into pages and sections that the user can navigate — everything you need to build a complete application is included in one cohesive framework.

• Integrated testing: Angular includes the tools to test your app out of the box, so that you can perform unit and end-to-end testing without having to configure testing libraries yourself. 

• Start with a clean slate: This might be a little controversial, but having to do things the Angular way does force you to organize your code. This can be really useful, especially if you use Angular in other projects: you'll always be oriented in your code base and know where to look for things, which can make it much easier to update your code months (or years!) later.

React vs. Angular: similarities and key differences for developers

Before getting into the practical differences between React and Angular, it's first worth mentioning their biggest similarity: both fit into a component-based architecture, also known as a composable architecture. This is a methodology for building applications that focuses on reusable parts.

This focus extends from the front end to the backend, and includes components that you write yourself, components provided by open-source libraries (like React and Angular), as well as third-party services that integrate with your projects to add functionality without you having to write any code yourself (like Contentful for hosting your content and providing your backend API for you).

As discussed above, React and Angular both provide the tools for building responsive and interactive user interfaces, but that's where React's functionality ends. To build a fully functional application in React, you will need to add additional libraries (for example, React Router for client-side routing and Axios for making HTTP requests) to your project, as well as writing additional supporting code to retrieve data and manage your application state.

This is seen as a benefit by some, who want greater flexibility in the choice of tools they use. It allows you to either use React as a ”light touch” — building smaller interactive sites, and adding interactivity to apps built with an assortment of technologies underpinning them — or give it a more central role by extending it to build out an entire application.

In the context of the MVC (model-view-controller) application model, which encourages splitting code into model (data handling), view (user interface), and controller (data transformation and processing) components, React is almost entirely focused on the view side of things, whereas Angular provides a whole MVC stack. Some developers prefer this, especially if they want to be up and running quickly and have heavier requirements where a whole MVC framework is suitable.

As for your end users — the most important people to consider when developing an application — they won't notice a difference. Both React and Angular and their ecosystems can be used to build just about anything. But, depending on your requirements and the platforms you want to integrate, which one you choose can mean more or less work to get to the end goal.

React vs. Angular: in-depth comparison

Technical debt is something every developer dreads, and while it is often unavoidable, it can be minimized by choosing the right tools from the outset. It can be a big waste of resources (and very frustrating) to have to rip up all of the work you’ve put into a project because one of the components you chose early in the development process doesn't meet your needs. Beyond the intended use cases for React and Angular, you should also consider whether they include (or have robust supporting libraries that can add) functionality that you require now, and in the future.

One thing that isn't directly comparable, but makes a huge difference and should be factored in when you're deciding what library or framework to base your codebase on, is inertia. If you, someone on your team, or a friend are already familiar with either React or Angular, the learning curve and community support metric changes: having someone on your Discord, Slack, or even in the next office cubicle to help you figure something out is invaluable!

Which one should you learn if you’re learning to code?

Learning to code isn't so much about the specific language, platform, or libraries you choose: it's about learning to think in programming terms, solving problems using programming logic, and establishing best practices. You can then apply those concepts to any programming language and project — it's usually just a matter of figuring out new syntax.

However, from a practical standpoint, if you're just learning how to program, less is more. React provides a good starting point because it lets you start small, building simple components that you can test and experiment within your browser. From there, you can build more complex components, and start exploring more advanced concepts like retrieving data from APIs and showing it on the page, until you have a full working application. It also lets you use regular JavaScript to build your components, which is easier for beginners.

Angular, being a full framework, is less ideal for learning as you need to understand how the whole framework behaves to be able to start using it. It has a steeper learning curve, which can be amplified by its use of TypeScript, which those starting out may not yet be familiar with.

If, however, you're already a proficient programmer and just looking to learn a new tool to enhance your front ends or further your career, you should choose the one that looks most appropriate for your situation by considering whether Angular or React is standard in the industry sector you’re targeting.

Choosing between React and Angular for your project

When choosing between React and Angular for a new project, you need to identify your project requirements and find out which of the frameworks best meets them. The first and most important consideration is whether your project is already established:

• Existing projects: React is often the best choice as you can add it to your existing codebase and start using it to add interactivity to your pages, gradually applying it as required.

• New projects: Angular is really only practical if you're starting a project from scratch or planning to rewrite your application.

After this, you can start to weigh other considerations, such as which best suits your development style, whether anyone on your team already has experience with React or Angular, and whether either option has an ecosystem of supporting libraries and pre-built components better suited to your specific use case (for example, you may want to use a specific date picker widget that is only supported by React). 

Support from the third-party platforms you use is also important. While Contentful can be used with any JavaScript front end, we provide a lot of our tutorials and tooling based on React as it's the library we see demanded most by our users.

Top React and Angular resources

React and Angular both provide extensive documentation to help you learn how to build apps, alongside tutorials provided by their communities. They also have a huge ecosystem of libraries including pre-built user interface components, SDKs for interacting with online content, payment, and ecommerce, and other online services, all of which can be leveraged to get your product up and running much faster than would be possible by developing from scratch.

One special mention is the Ionic framework, which lets you build web and mobile apps (that can even be packaged for submission to Android and iOS app stores!) from a single codebase, using either React or Angular. It's a force multiplier for small and large development teams, providing a fully functional app template with working pages, buttons, and data services out of the box so that you can get straight to building your frontend user experience and connecting your backend services.

Choosing the right backend services for your React/Angular websites and mobile apps

Once you've chosen between React and Angular and started planning out the rest of your application and the frontend and backend components you’ll need to build it, you'll need to decide how you'll host your code and deliver your content. 

The fastest and most performant way to deliver your app to your users is to build a static front end that can be hosted on an affordable and scalable CDN. For your backend, rather than writing and maintaining your own services, you can extend your composable architecture to your backend and choose services like Contentful to manage and deliver your content to your users’ devices from a central platform, streamlining content management, curation, and delivery. 

A composable architecture based on React or Angular that leverages established third-party backends lets you get on with the job of developing the most important part of your project: the frontend user interface that engages and retains your valuable users.

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