Generators in JavaScript are essentially functions that can pause and resume their execution while maintaining function-scope. But in ReactJS, mainly we write normal synchronous code and use states and life cycle methods to manage asynchronicity.
However, there are scenarios where we want to manage our side effects and use Generators with ReactJS like in the case of redux-saga.
The below example demonstrates how you can use redux-saga, a library for managing Redux app side effects, with generators:
1. Install redux-saga:
`npm install redux-saga`
1. Create a Saga file
```
//sagas.js
import { call, put, takeEvery, takeLatest } from ‘redux-saga/effects’
// Fetch data from API
function* fetchData(action) {
try {
const data = yield call(Api.fetchUser, action.payload.url);
yield put({type: “FETCH_SUCCEEDED”, data});
} catch (error) {
yield put({type: “FETCH_FAILED”, error});
}
}
// Watch for the fetchData action and start fetchData function
function* watchFetchData() {
yield takeEvery(“FETCH_REQUESTED”, fetchData);
}
export default function* rootSaga() {
yield all([
watchFetchData()
]);
}
```
1. Then you should run this Saga in your application.
You can do this by following these steps:
a. First, import the sagaMiddleware from redux-saga and create the Saga middleware with the created saga:
```
// store.js
import createSagaMiddleware from ‘redux-saga’;
import { createStore, applyMiddleware } from ‘redux’;
import reducer from ‘./reducers’;
import rootSaga from ‘./sagas’;
const sagaMiddleware = createSagaMiddleware();
const store = createStore(
reducer,
applyMiddleware(sagaMiddleware)
);
sagaMiddleware.run(rootSaga);
```
b. Now, you can dispatch actions from your React component as you normally do:
```
//Component.js
import React from ‘react’;
import { connect } from ‘react-redux’;
class SomeComponent extends React.Component { componentDidMount() { this.props.dispatch({type: “FETCH_REQUESTED”, payload: {url: ‘https://some-api’}}); }
//… }export default connect()(SomeComponent);
```
Note: While you can use Generators in React JS, they are not as commonly used compared to other features in JavaScript ES6+. If you find yourself needing to use Generators, it may be a signal that you might need to research a better way or a library that fulfills your requirements.
