Redux vs Redux Observable: What are the differences?

Introduction

In this article, we will discuss the key differences between Redux and Redux Observable. These two libraries are commonly used for managing state in JavaScript applications.

1. Redux: Redux is a predictable state container for JavaScript apps. It provides a centralized store for managing the application state and a set of rules for updating that state in a predictable manner. Redux follows a unidirectional data flow pattern, where actions are dispatched to modify the state, and components subscribe to updates in the state to reflect the changes.

2. Redux Observable: Redux Observable is an extension of Redux that introduces the concept of observables for handling asynchronous actions. It is built on top of the reactive programming library called RxJS. Redux Observable allows you to express complex asynchronous logic using a declarative, functional programming style.

3. Difference 1: Middleware: Redux uses middleware, such as thunk or saga, to handle asynchronous actions. These middleware intercept the dispatched actions and perform additional logic before reaching the reducer. On the other hand, Redux Observable eliminates the need for middleware by using observables. With Redux Observable, you can handle async actions directly in your epics (observables) without the need for additional middleware.

4. Difference 2: Declarative vs Imperative: Redux follows an imperative style of programming, where you define actions and reducers to modify the state. Redux Observable, on the other hand, follows a declarative style of programming with the use of observables. In Redux Observable, you define epics that listen to specific actions and respond with new actions, allowing you to express complex asynchronous logic in a more concise and readable manner.

5. Difference 3: Granularity: Redux operates at a fine-grained level, requiring you to dispatch actions for every state mutation. This can lead to more verbosity and boilerplate code, especially for large applications. Redux Observable, on the other hand, allows you to handle multiple related actions in a single epic. This provides a higher level of abstraction and reduces the amount of code needed to manage complex state changes.

6. Difference 4: Composition: With Redux Observable, you can easily compose multiple epics together to handle different parts of your application's state. This allows for better separation of concerns and modularity. In Redux, composing reducers can be more challenging and often requires the use of additional libraries or patterns.

7. Difference 5: Testing: Testing asynchronous code in Redux can be cumbersome, as you need to mock the asynchronous dependencies and manually dispatch actions in the correct order. Redux Observable simplifies testing by providing a way to test your epics in isolation. You can easily assert on the emitted actions and test the logic of your epics without the need for complex setup.

In summary, Redux is a predictable state container that uses middleware for managing async actions, while Redux Observable extends Redux with observables for handling asynchronous logic in a declarative manner. Redux operates at a fine-grained level, while Redux Observable provides a higher level of abstraction. Redux Observable also simplifies testing and allows for easier composition of epics.