Pros/cons of using redux-saga with ES6 generators vs redux-thunk with ES2017 async/await

javascript

async-programming

state-management

redux

byNikita Barsukov·Mar 3, 2025

For quick async tasks, use redux-thunk and async/await:

const fetchData = () => async dispatch => {
  dispatch({ type: 'FETCH_START' });
  try {
    const data = await fetchAPI(); // "Playing fetch with API" 😆
    dispatch({ type: 'FETCH_SUCCESS', data });
  } catch (error) {
    dispatch({ type: 'FETCH_FAIL', error });
  }
};

For intricate processes that need yield, like cancellation or start/stop tasks, go for redux-saga:

function* fetchUserData() {
  try {
    yield put({ type: 'FETCH_START' }); // And here the FETCH_START shines ☀
    const data = yield call(fetchAPI); // "Hi, fetchAPI? Please do the thing" 📞
    yield put({ type: 'FETCH_SUCCESS', data });
  } catch (error) {
    yield put({ type: 'FETCH_FAIL', error }); // "So, we had a slight setback" 🚨
  }
}

Easy async with async/await. Fine-grained control with yield.

Specifics: redux-saga vs. redux-thunk

Final decisions between redux-saga and redux-thunk relies on what your project requires, as well as your team's familiarity with the tools. If you need to handle tricky situations like race conditions, or parallel requests, redux-saga might be your best bet, offering a structured approach to "A affects B" async flows.

On the other hand, Redux-thunk excels in less complicated situations where async/await suffices. This suits smaller projects, where side effects won’t lead to maintainability nightmares.

Testing & Maintenance Made Easier

Testing with redux-saga is straightforward. You can mock data by returning pure objects from tests, rather than mimicking whole thunk functions. This encourages good TDD habits and improves your code.

With yield, generators allow you to write sync-like code for async tasks. Reading the flow of operations, even when they’re async, is easier. Together with redux-saga's selection of helper effects, effect management becomes more clear cut.

Control of Complexity

As applications grow complex, redux-thunk can become a catch-all controller. Here, redux-saga comes in handy to maintain a clear separation of concerns. Sagas act independently, reacting to actions in the background while remaining decoupled from action creators, reducers, and the UI.

Redux-saga also stands out by providing event-channel to manage non-Redux actions, such as web sockets or other callback-based events. This flexible feature stands out when addressing side-effect management.

Advance with Advanced Control Flows

Using redux-saga, developers can implement advanced asynchronous control flows like debouncing or throttling. Redux-saga even supports tasks like starting, stopping, and cancellation, which are hard to achieve with redux-thunk.

Sagas: The Background Thread Workers

Think of sagas as background threads in your JavaScript application. Just like scouts, they handle effects behind the scenes, detached from the main application logic. This cohesion with react-redux architecture boosts redux-saga's efficiency in state management.

Visualization

Managing a team of messengers delivering messages can look something like this:

| Mechanism       | Team            | Workflow                                   |
| ----------------| --------------- | ------------------------------------------ |
| **redux-saga**  | 🚴‍♂️ 🔄 Generator  | 📜 Ticks off each task, handling them cautiously. |
| **redux-thunk** | 🏃‍♂️ 💨 Async/Await | 💌 Dashes off with messages, no looking back. |

With Generators: It's all about pauses and thoughtfulness.

🚴‍♂️ => 🛑 Take task => 🔄 Handle task => 🛑 Pause => 🔄 Next Task
# Every step deliberated; control over the process.

With Async/Await: It's a seamless, continuous action.

🏃‍♂️ => 💌 Fast Delivery => 🏃‍♂️ => 💌 Next in Queue
# Just like our office coffee runner, doesn’t stop!

Whether you choose a meticulous bicycle courier or a swift sprinter, each decision comes with its own pros and cons.

Navigating Growth and Complexity

Thunks can get clunky as application complexity grows. If your application has interrelated async operations, consider redux-saga to avoid tedious refactoring down the road.

Concurrent processes are well-managed effectively by redux-saga. Starting from handling multiple instances of a saga to orchestrating race conditions, redux-saga is made for concurrency.

For larger applications with significant side effects management, sagas offer a smoother ride. The declarative style and structured approach to handling effects keep the code clean and maintainable, which might not be the case inside thunks.

Handling the Learning Curve and Developer Experience

Redux-saga has a steeper learning curve. But the upfront cost balances out with a strong, scalable approach to state management. Beginners or small projects with simple state can strike gold with the quick setup and simplicity of Redux-thunk.

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