redux-saga
A Redux middleware that manages side effects like data fetching using generator functions.
- Stars
- 22.4k
- Forks
- 1.9k
- Licence
- MIT
- Language
- JavaScript
- Last update
- 12 days ago
- Type
- Library
What it is
redux-saga is a library for Redux apps that handles side effects, such as fetching data from a server or reading from the browser cache. It runs as Redux middleware, so background tasks ('sagas') can be started, paused, or cancelled by normal Redux actions, and can read state or dispatch actions. It uses JavaScript generator functions so asynchronous code reads like ordinary step-by-step code.
- Fetch user data when a button is clicked, with a saga watching for a 'USER_FETCH_REQUESTED' action
- Choose between takeEvery (allow concurrent fetches) and takeLatest (cancel the pending fetch when a new one starts)
- Dispatch success or failure actions after an API call completes
- Run the example apps in the repository (counter, shopping cart, async) to see patterns in action
Great for
- React or other frontend developers already using Redux who need to manage async logic
- Teams that want asynchronous flows that are easy to test
- Apps where side effects need cancellation, such as cancelling a pending fetch when a new one starts
- Developers who have found redux-thunk callbacks hard to organize
Not ideal for
- Apps that do not use Redux, since the library is built as Redux middleware
- Developers who want to avoid learning generator functions, which the README says the project chose over async/await
- Simple apps with only a few API calls, where a lighter approach may be enough
How to get it
- 1
Install with a package manager
Install with npm
npm install redux-sagaInstall with yarn
yarn add redux-saga - 2
Run it
- Install the package with npm or yarn
- Create a saga generator function that watches for an action type using takeEvery or takeLatest
- Create the saga middleware with createSagaMiddleware() and apply it to the Redux store
- Run the root saga with sagaMiddleware.run()
- 3
Get the most out of it
- Read the Introduction and Basic Concepts sections of the official documentation at redux-saga.js.org
- Use the declarative effects (call, put, takeEvery, takeLatest) to keep sagas easy to test
- Use the cancellable-counter example to learn task cancellation
- Check the External Resources page if you are new to generators
Downloads
Strengths
- Asynchronous flows are written as readable, synchronous-looking code using generators
- Sagas can be cancelled and tested, according to the README
- Keeps action creators and reducers free of side effect logic
Trade-offs
- Requires understanding generator functions and the saga concepts, which have a learning curve
- The README describes a specific design choice (generators over async/await) that some developers may not prefer
- README is truncated, so detailed API behavior must be checked in the external documentation
How it compares
| Project | Stars | Type | Level | Updated | Best for |
|---|---|---|---|---|---|
| redux-saga (this) | 22.4k | Library | intermediate | 12 days ago | React or other frontend developers already using Redux who need to manage async logic |
| redux-thunk | 17.7k | Library | intermediate | 1.6 years ago | Developers building apps with Redux who need async logic such as API calls |
| dva | 16.1k | Library | intermediate | 1.3 years ago | React developers already familiar with Redux who want less boilerplate |
| react-boilerplate | 29.4k | Framework | advanced | 3.6 years ago | Experienced React developers starting a new production web app |
| reactotron | 15.6k | Dev tool | intermediate | 3 months ago | React Native developers who want to see app state and network calls while debugging |
| redux | 61.4k | Library | intermediate | 17 days ago | Developers building larger front-end apps where many components share the same data |
Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.