AngularJS vs. ReactJS: Key Differences and Migration Considerations

AngularJS has reached community support end of life, leaving many companies who have yet to migrate from AngularJS quickly searching for a suitable migration path. Unfortunately, migrations from AngularJS are more akin to a rewrite than a typical migration. That means finding an AngularJS alternative that minimizes the difficulty and extent of a rewrite important. However, finding a framework that also aligns with the functionality of the application and offers a stable, long-term platform for ongoing innovation is just as important.

In this blog, we compare some of the features and functionalities of AngularJS vs. ReactJS, with special attention to factors that will impact migration decisions.

AngularJS vs. ReactJS: Key Similarities

At their core, AngularJS and ReactJS attempt to solve very similar problems: How can developers be best enabled to build the front-end of their web applications. Given this, it’s not surprising that some similarities appear. They’re both written in JavaScript, open source, and front-end libraries. More importantly, both solve this problem by providing tools for building a view from your data and allowing changes to be propagated back. However, this is where the major similarities end.

AngularJS vs. ReactJS: Key Differences

As mentioned above, despite both being JavaScript-based application frameworks, AngularJS and ReactJS take significantly different approaches in everything from scope and architecture to functionality and flexibility.

Scope and Complexity

AngularJS can be a rather large and complex beast. It enforces a MVC architecture and tends to be rather opinionated about the structure and flow of your application. This combined with its large scale means developers must learn quite a bit before feeling comfortable with it. This has given AngularJS the reputation of having a rather steep learning curve.

ReactJS, by comparison, keeps simple and narrow in scope. It focuses on providing a lightweight tool for component rendering, and leaves additional functionality to other libraries and frameworks, such as Redux. However, what it lacks in scale it makes up for in ease of use and flexibility. While this may cause some challenges for applications deep into AngularJS’s ecosystem when migrating, it can also be a boon for those who need the simplest and fastest alternative to get started with. That's especially true for for web applications that are smaller in size.

Performance

A common point of concern for any new framework is performance. Thankfully this is an area where ReactJS shines. ReactJS utilizes a virtual DOM to allow rapid changes without invoking the cost of interacting with the DOM. This can then be used to selectively update pieces of the DOM with a much lower performance penalty.

Of course performance is a complicated subject, and the speed at which the page can be updated is only one part of that. ReactJS’s smaller size can help with load times, and its unidirectional bindings help application performance scale better as the complexity increases. That said, performance will depend on your particular use case and the architectural decisions made. Migrating an existing large application to ReactJS will not necessarily see improvements, but instead provides new opportunities for optimization.

AngularJS Is MVC, ReactJS Is Just “V”

As touched on previously, one of the largest differences between AngularJS and ReactJS is the architecture they use. AngularJS structures itself after a model-view-controller architecture and allows for bidirectional data-binding. These two together push applications towards a particular structure and mentality.

ReactJS, in contrast, does not have such a fixed architecture. Instead it focuses primarily on the “view” portion of model-view-controller and leaves most things to the developer to decide. This combined with the unidirectional flow of data creates an easy to use and understand library. However, this simplicity comes at a cost. Those attempting to migrate from AngularJS to ReactJS may find their application structure incompatible and may need to consider deep architectural changes to take full advantage of what ReactJS and its ecosystem have to offer.

Flexibility

One of the most appealing points to ReactJS is the level of flexibility it offers. With its narrow scope, ReactJS can fit easily into other tools and systems without fighting the library itself. This allows for ReactJS to accommodate a wide range of application sizes and types. Small applications looking for a cleaner, more dynamic content rendering tool will find ReactJS offers everything they need. While others looking for a more complete tool can simply choose to include popular libraries such as Redux for a more complete experience.

AngularJS, as full featured as it is, mostly expects its developers to use the provided tools. If it happens to fit your needs, this can be fantastic. Who doesn’t want a single framework to handle everything? However, if it doesn’t, you can be left fighting the framework itself to accomplish what may seem like a basic need.

AngularJS to ReactJS Migration Considerations

Ultimately, when looking to migrate from AngularJS one of the first questions should be: “What parts of AngularJS are most important to my application?” If the answer involves the MVC architecture, bi-directional bindings, or extensive usage of AngularJS’s features, then a move to ReactJS may be more effort than it’s worth. On the other hand, if most of your complexity is deep within the business logic, you may find ReactJS’s lightweight and easy to learn component rendering a strong choice for migration.

Additionally, should you choose to proceed with ReactJS, it’s important to ensure that the functionality you need is available in an acceptable form. As an example, ReactJS does not provide functionality for asynchronous requests, instead this is available through 3rd party libraries such as react-async.

Final Thoughts

For obvious reasons, most people reading this article will be reading it with a migration from AngularJS to ReactJS in mind. That makes it doubly important to consider the needs of the application and how ReactJS can be applied. As mentioned above, ReactJS isn’t an MVC framework and won’t be a good choice if you need a like for like replacement for AngularJS.

Additional Resources

• Blog - How to Choose a JavaScript Framework to Replace AngularJS
• Blog - Top Open Source Frameworks From the State of Open Source Report
• Blog - What Is AngularJS?
• Blog - AngularJS vs. VueJS: How They Compare
• Blog - AngularJS vs. Node.js: Understanding the Key Differences
• Blog - Planning for AngularJS EOL
• On-Demand Webinar - What You Need to Know About AngularJS EOL
• Blog - Angular vs. AngularJS
• Blog - AngularJS vs. Ember.js