reduxsaga

Redux-Saga is a library for managing side effects in applications that use Redux. It enables handling asynchronous operations such as data fetching, background tasks, and other non-blocking workflows in a predictable, testable manner.

The core idea is to run sagas, which are generator functions, inside a Redux middleware. Sagas yield declarative effect objects (such as call, put, take, and all) that describe side effects rather than performing them directly. A saga middleware interprets these effects and executes the corresponding asynchronous operations, dispatching actions and coordinating concurrency.

Common patterns include watching for specific actions with takeEvery or takeLatest, performing calls with call to promise-returning functions, dispatching actions with put, and composing multiple effects with all. Sagas can run concurrently, be cancelled, and read state via select. The approach favors testability, because the saga yields plain objects that can be inspected in tests.

Usage and integration: install redux-saga, apply the saga middleware to the Redux store, and run one or more root sagas with sagaMiddleware.run(rootSaga). Sagas can be started once and continue listening for actions or be started and stopped dynamically. It is commonly used in React-Redux apps but is framework agnostic.

Advantages and considerations: redux-saga provides fine-grained control over complex asynchronous flows and easy cancellation. However it introduces generator-based code and a separate middleware layer, which can increase learning curve and boilerplate relative to simpler patterns like thunks.