redux-saga

What is redux-saga?

redux-saga is a library that aims to make application side effects (i.e., asynchronous things like data fetching and impure things like accessing the browser cache) easier to manage, more efficient to execute, and better at handling failures. It uses an ES6 feature called Generators to make those asynchronous flows easy to read, write, and test.

What are redux-saga's main functionalities?

Handling Asynchronous Actions

This feature allows you to handle asynchronous actions in a more readable and maintainable way. The code sample demonstrates how to fetch user data asynchronously using the `call` effect to call the API and `put` effect to dispatch actions.

function* fetchUser(action) {
  try {
    const user = yield call(Api.fetchUser, action.payload.userId);
    yield put({type: 'USER_FETCH_SUCCEEDED', user: user});
  } catch (e) {
    yield put({type: 'USER_FETCH_FAILED', message: e.message});
  }
}

function* mySaga() {
  yield takeEvery('USER_FETCH_REQUESTED', fetchUser);
}

Managing Side Effects

redux-saga helps manage side effects like delays, API calls, and more. The code sample shows how to delay an increment action by 1 second using the `delay` effect.

import { delay } from 'redux-saga/effects';

function* incrementAsync() {
  yield delay(1000);
  yield put({ type: 'INCREMENT' });
}

function* watchIncrementAsync() {
  yield takeEvery('INCREMENT_ASYNC', incrementAsync);
}

Handling Concurrency

redux-saga provides tools to handle concurrency, ensuring that only the latest action is processed. The code sample demonstrates using `takeLatest` to handle only the most recent fetch request.

import { takeLatest } from 'redux-saga/effects';

function* fetchData(action) {
  try {
    const data = yield call(Api.fetchData, action.payload);
    yield put({ type: 'FETCH_SUCCEEDED', data });
  } catch (error) {
    yield put({ type: 'FETCH_FAILED', error });
  }
}

function* mySaga() {
  yield takeLatest('FETCH_REQUESTED', fetchData);
}

Other packages similar to redux-saga

redux-thunk

redux-thunk is a middleware that allows you to write action creators that return a function instead of an action. It is simpler and more lightweight compared to redux-saga, but it doesn't offer the same level of control over complex asynchronous flows.

redux-observable

redux-observable is an RxJS-based middleware for Redux that allows you to work with async actions using Observables. It is more powerful and flexible than redux-saga for handling complex async logic, but it has a steeper learning curve due to its reliance on RxJS.

rematch

rematch is a Redux framework that abstracts away much of the boilerplate associated with Redux. It includes built-in support for side effects and async actions, making it easier to use than redux-saga, but it may not offer the same level of customization and control.

README

redux-saga

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