Back in 2011, when my code became cluttered with jQuery selectors and callbacks, AngularJS emerged as a lifesaver. It greatly improved code organization, sped up development, and offered a wealth of out-of-the-box features. I was particularly impressed by AngularJS’s two-way binding and the “model as the single-source-of-truth” philosophy, which drastically reduced data redundancy in my application.

However, as time passed, I began to encounter some drawbacks with AngularJS, eventually leading me to explore alternative solutions.

Challenges with AngularJS 1.x

• DOM-Dependent Execution

  Angular relies heavily on the DOM for its execution flow. During the default bootstrapping process, it scans and compiles the DOM based on directive priorities, making it challenging to debug and test the execution order.

• Proprietary Dependency Injection

  Unlike modern JavaScript, AngularJS doesn’t seamlessly integrate with standard dependency management solutions like AMD, UMD, or CommonJS. Instead, it introduces its own dependency injection (DI) system, although unofficial implementations using RequireJS exist.

• Two-Way Binding: A Double-Edged Sword

  While convenient, two-way binding in AngularJS can negatively impact performance, especially as component complexity grows. Since JavaScript ES5 lacks change notification mechanisms, Angular employs “dirty checking” to synchronize data changes with the UI. This process occurs after every operation within Angular’s scope ($digest cycle), leading to performance degradation as the number of bindings increases.

  Additionally, two-way binding can introduce ambiguity if multiple components can modify the same data, potentially creating multiple sources of data input. It’s worth noting that this is more of an implementation challenge than a fundamental flaw.

• Living in an Angular World

  In Angular, every operation must go through its digest cycle for components to stay in sync with data models. Consequently, integrating third-party JavaScript libraries often requires wrapping them with Angular’s $apply function or converting them into services. This can feel like reinventing the wheel for existing JavaScript modules.

• Steep Learning Curve

  Mastering AngularJS involves grasping numerous concepts such as modules, controllers, directives, scopes, templates, linking functions, filters, and dependency injection.

Enter React

React, the open-source JavaScript library developed by Facebook and Instagram, offers a fresh perspective on building web applications. Its introduction at JSConf EU in May 2013 surprised many with its unique design principles, such as “one-way data flow” and the “Virtual DOM.”

As stated on the official React website, “React is a JavaScript library for building user interfaces.” It’s not a full-fledged framework like AngularJS. However, it empowers developers to create self-contained components, conceptually similar to Angular directives.

React challenges conventional web development practices. It champions one-way data flow and views components as state machines driven by data. While other frameworks often directly manipulate the DOM, React abstracts it away, providing a layer of insulation for developers. The library offers a minimal API focused solely on defining UI components, adhering to the UNIX philosophy: “Small is beautiful. Do one thing and do it well.”

This is a very nice comparison between the two by Pete Hunt (from Instagram team)

React as a Library: The Need for a Framework

In short: It’s your call.

React excels at building user interfaces, but what about managing dependencies, making AJAX calls, or applying data filters? If a framework is necessary, why not stick with AngularJS?

Frameworks impose a set of packages and rules. But what if you need to swap out or omit certain packages? That’s where a package manager comes in. AngularJS offers limited options in this regard, as it operates within its own ecosystem, often requiring wrapping external packages for compatibility.

In contrast, React’s reliance on standard JavaScript enables seamless integration with existing packages from repositories like npm. This flexibility allows you to handpick and organize packages according to your needs. Thankfully, React actively encourages npm usage, providing access to a vast collection of ready-to-use packages. For those starting with React, utilizing tools like these Full-Stack Starter Kits can streamline the development process.

Benefits of React

So, why did I make the switch?

Speed is Key

React’s approach differs significantly from traditional frameworks. Instead of directly interacting with the DOM, it introduces the Virtual DOM—an intermediary layer between your JavaScript logic and the actual DOM. This abstraction significantly improves performance. During subsequent rendering cycles, React performs a “diff” operation on the Virtual DOM, updating only the necessary parts of the real DOM, resulting in faster updates and smoother user experiences.

Furthermore, the Virtual DOM helps address cross-browser compatibility issues by providing a unified API that functions seamlessly even in older browsers like Internet Explorer 8.

Component-Based Architecture

Building applications with self-contained UI components promotes modularity and separation of concerns. Each component can be developed and tested independently, fostering maintainability and reusability within your project.

Embracing One-Way Data Flow

Flux, an architecture designed alongside React, promotes one-way data flow in JavaScript applications. This approach simplifies development, enhances predictability, and makes debugging more straightforward. While closely associated with React, Flux is a conceptual pattern applicable to other frameworks as well. For instance, Alex Rattray demonstrates a compelling Flux implementation using Backbone Collection and Model in React.

JavaScript-Centric Development

Modern web apps often demand dynamic updates without constant server requests, necessitating close collaboration between the view and controller layers. Many frameworks utilize templating engines like Handlebars and Mustache for view management. React, however, argues for tight integration between these layers, advocating for a unified JavaScript-centric approach without relying on external templating engines.

Isomorphic JavaScript for SEO

A common drawback of single-page JavaScript applications is their limited crawlability by search engines. React addresses this issue by enabling server-side pre-rendering. This means your application can be partially rendered on the server before being sent to the browser, improving SEO by providing crawlers with meaningful content. Additionally, React can seamlessly restore the application’s state from this pre-rendered content.

Seamless Integration with Module Bundlers

Large-scale applications benefit from module loaders and bundlers. While the current JavaScript specification lacks a built-in solution (although proposed for ECMAScript 6 (System.import)), alternatives like RequireJS and Webpack provide excellent alternatives.

React integrates smoothly with Browserify out of the box. However, if you need advanced features like asset injection, LESS/CoffeeScript compilation, or code splitting, Webpack might be a more suitable choice.

Transitioning to React: Challenges and Considerations

• AngularJS, being a framework, offers many built-in features like the $http service for AJAX requests, $q for promises, and directives like ng-show, ng-hide, ng-class, and ng-if for template manipulation.

• React, as a UI library, requires you to handle these aspects yourself. Thankfully, projects like an open source project, which I’m currently involved in, aim to bridge this gap and simplify React development. The community actively contributes to such reusable components as well.

  You can find a curated list of open-source React components on unofficial directory websites like React-components.com.

• React’s philosophy discourages two-way binding, which can initially feel cumbersome when working with forms and editable data grids. However, as you embrace Flux and the concept of Stores, managing data flow becomes more intuitive and manageable.

A Growing Community

AngularJS, with its established presence, boasts a large community and a vast ecosystem of extensions like AngularUI and Restangular. While React’s community is relatively new, it’s rapidly expanding, with noteworthy extensions like React Bootstrap emerging. As the community matures, we can expect a richer selection of readily available components, further simplifying and accelerating React development.

Final Thoughts

If you’re accustomed to AngularJS, React might initially feel unfamiliar, particularly its one-way data flow and the need to handle certain aspects traditionally covered by frameworks. However, as you become familiar with Flux and React’s design principles, you’ll begin to appreciate its elegance and efficiency.

Prominent companies like Facebook](https://www.facebook.com/) and Instagram heavily rely on React. Github’s new Atom Editor is a testament to its capabilities. Even the upcoming Yahoo Mail is being rebuilt using React. With such compelling examples, why not [give React a try today?