npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

@vve/redux-saga

v9.2.1

Published

Saga middleware for Redux to handle Side Effects

Downloads

458

Readme

redux-saga

npm version CDNJS npm Build Status Join the chat at https://gitter.im/yelouafi/redux-saga OpenCollective OpenCollective

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, simple to test, and better at handling failures.

The mental model is that a saga is like a separate thread in your application that's solely responsible for side effects. redux-saga is a redux middleware, which means this thread can be started, paused and cancelled from the main application with normal redux actions, it has access to the full redux application state and it can dispatch redux actions as well.

It uses an ES6 feature called Generators to make those asynchronous flows easy to read, write and test. (if you're not familiar with them here are some introductory links) By doing so, these asynchronous flows look like your standard synchronous JavaScript code. (kind of like async/await, but generators have a few more awesome features we need)

You might've used redux-thunk before to handle your data fetching. Contrary to redux thunk, you don't end up in callback hell, you can test your asynchronous flows easily and your actions stay pure.

Getting started

Install

$ npm install --save redux-saga

or

$ yarn add redux-saga

Alternatively, you may use the provided UMD builds directly in the <script> tag of an HTML page. See this section.

Usage Example

Suppose we have a UI to fetch some user data from a remote server when a button is clicked. (For brevity, we'll just show the action triggering code.)

class UserComponent extends React.Component {
  ...
  onSomeButtonClicked() {
    const { userId, dispatch } = this.props
    dispatch({type: 'USER_FETCH_REQUESTED', payload: {userId}})
  }
  ...
}

The Component dispatches a plain Object action to the Store. We'll create a Saga that watches for all USER_FETCH_REQUESTED actions and triggers an API call to fetch the user data.

sagas.js

import { call, put, takeEvery, takeLatest } from 'redux-saga/effects'
import Api from '...'

// worker Saga: will be fired on USER_FETCH_REQUESTED 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});
   }
}

/*
  Starts fetchUser on each dispatched `USER_FETCH_REQUESTED` action.
  Allows concurrent fetches of user.
*/
function* mySaga() {
  yield takeEvery("USER_FETCH_REQUESTED", fetchUser);
}

/*
  Alternatively you may use takeLatest.

  Does not allow concurrent fetches of user. If "USER_FETCH_REQUESTED" gets
  dispatched while a fetch is already pending, that pending fetch is cancelled
  and only the latest one will be run.
*/
function* mySaga() {
  yield takeLatest("USER_FETCH_REQUESTED", fetchUser);
}

export default mySaga;

To run our Saga, we'll have to connect it to the Redux Store using the redux-saga middleware.

main.js

import { createStore, applyMiddleware } from 'redux'
import createSagaMiddleware from 'redux-saga'

import reducer from './reducers'
import mySaga from './sagas'

// create the saga middleware
const sagaMiddleware = createSagaMiddleware()
// mount it on the Store
const store = createStore(
  reducer,
  applyMiddleware(sagaMiddleware)
)

// then run the saga
sagaMiddleware.run(mySaga)

// render the application

Documentation

Translation

Using umd build in the browser

There is also a umd build of redux-saga available in the dist/ folder. When using the umd build redux-saga is available as ReduxSaga in the window object. This enables you to create Saga middleware without using ES6 import syntax like this:

var sagaMiddleware = ReduxSaga.default()

The umd version is useful if you don't use Webpack or Browserify. You can access it directly from unpkg.

The following builds are available:

Important! If the browser you are targeting doesn't support ES2015 generators, you must transpile them (i.e. with babel plugin) and provide a valid runtime, such as the one here. The runtime must be imported before redux-saga:

import 'regenerator-runtime/runtime'
// then
import sagaMiddleware from 'redux-saga'

Building examples from sources

$ git clone https://github.com/redux-saga/redux-saga.git
$ cd redux-saga
$ npm install
$ npm test

Below are the examples ported (so far) from the Redux repos.

Counter examples

There are three counter examples.

counter-vanilla

Demo using vanilla JavaScript and UMD builds. All source is inlined in index.html.

To launch the example, just open index.html in your browser.

Important: your browser must support Generators. Latest versions of Chrome/Firefox/Edge are suitable.

counter

Demo using webpack and high-level API takeEvery.

$ npm run counter

# test sample for the generator
$ npm run test-counter

cancellable-counter

Demo using low-level API to demonstrate task cancellation.

$ npm run cancellable-counter

Shopping Cart example

$ npm run shop

# test sample for the generator
$ npm run test-shop

async example

$ npm run async

# test sample for the generators
$ npm run test-async

real-world example (with webpack hot reloading)

$ npm run real-world

# sorry, no tests yet

TypeScript

Redux-Saga with TypeScript requires DOM.Iterable or ES2015.Iterable. If your target is ES6, you are likely already set, however, for ES5, you will need to add it yourself. Check your tsconfig.json file, and the official compiler options documentation.

Logo

You can find the official Redux-Saga logo with different flavors in the logo directory.

Backers

Support us with a monthly donation and help us continue our activities. [Become a backer]

Sponsors

Become a sponsor and get your logo on our README on Github with a link to your site. [Become a sponsor]