redux-side-effects.md

Redux Side Effects

Basic Concepts

• Stack Overflow: Dispatching Redux Actions with a Timeout
  http://stackoverflow.com/questions/35411423/how-to-dispatch-a-redux-action-with-a-timeout/35415559#35415559
  Dan Abramov explains the basics of managing async behavior in Redux, walking through a progressive series of approaches (inline async calls, async action creators, thunk middleware).

• Stack Overflow: Why do we need middleware for async flow in Redux?
  http://stackoverflow.com/questions/34570758/why-do-we-need-middleware-for-async-flow-in-redux/34599594#34599594
  Dan Abramov gives reasons for using thunks and async middleware, and some useful patterns for using thunks.

• Pure Functionality and Side Effects with Redux
  https://blog.hivejs.org/building-the-ui-2/
  An overview of what side effects are, how they fit into Redux, and several approaches for managing them.

• "Async Redux workflow: calling actions outside Redux?"
  https://www.reddit.com/r/reactjs/comments/4upe9t/async_redux_workflow_calling_actions_outside_redux/d5sgy5s?context=3
  A comment explaining why using action creator functions is a good practice

• Why doesn't Redux support AJAX out of the box?
  http://goshakkk.name/redux-no-ajax-by-default/
  Looks at how AJAX calls fit into a Redux application

• Adding Customized Asynchrony to Redux
  https://anyperk.engineering/im-lauren-and-i-m-a-frontend-apprentice-here-at-anyperk-a1a40106d231
  A quick introduction to some of the libraries that can be used to manage asynchronous behavior in Redux.

Thunks

• What the heck is a "thunk"?
  https://daveceddia.com/what-is-a-thunk/
  A quick explanation for what the word "thunk" means in general, and for Redux specifically.

• Thunks in Redux: The Basics
  https://medium.com/fullstack-academy/thunks-in-redux-the-basics-85e538a3fe60
  A detailed look at what thunks are, what they solve, and how to use them.

• A Dummy's Guide to Redux and Thunk in React
  https://medium.com/@stowball/a-dummys-guide-to-redux-and-thunk-in-react-d8904a7005d3
  A tutorial that shows how to take a React component that does its own data fetching, and rework it to use accept data from Redux and use a thunk action creator instead.

• Understanding how redux-thunk works
  https://medium.com/@gethylgeorge/understanding-how-redux-thunk-works-72de3bdebc50
  An attempt to explain both redux-thunk and Redux's applyMiddleware enhancer, by rewriting the original implementations to add logging and rework names for ease of understanding.

• Async Actions with Redux Thunk Demystified
  http://blog.jakoblind.no/2017/04/25/async-actions-with-redux-thunk-demystified/
  A quick look at the source code for redux-thunk, how it works, and how to use it.

• Sense-ible Redux Thunk
  https://medium.com/sensehq/sense-ible-redux-thunk-30b866ca5914
  Examples of how to define reusable caching and authorization handling for thunks using decorators

• Returning promises from Redux action creators
  https://medium.com/collaborne-engineering/returning-promises-from-redux-action-creators-3035f34fa74b
  Shows how returning a promise from a thunk action creator allows the caller to chain off the promise and execute code after the action creator is complete.

• ReactCasts #10: Redux Thunk Tricks
  https://www.youtube.com/watch?v=xihoZZU0gao
  An excellent screencast that covers three useful tips for use of redux-thunk: thunk return values, multi-dispatch, and when to use getState

Side Effect Approach Comparisons

• Redux side effects and you
  https://medium.com/javascript-and-opinions/redux-side-effects-and-you-66f2e0842fc3
  Thoughts on the proliferation of new side effect libs for Redux, and some comparisons of the commonly used approaches.

• "Controversial opinion: redux-thunk is too powerful"
  https://twitter.com/intelligibabble/status/800103510624727040
  https://twitter.com/dan_abramov/status/800310164792414208
  Some discussion on the pros and cons of redux-thunk's flexibility and usage, as well as possible issues with multiple dispatches in a row.

• Idiomatic Redux: Thoughts on Thunks, Sagas, Abstractions, and Reusability
  http://blog.isquaredsoftware.com/2017/01/idiomatic-redux-thoughts-on-thunks-sagas-abstraction-and-reusability/
  A response to several "thunks are bad" concerns, arguing that thunks (and sagas) are still a valid approach for managing complex sync logic and async side effects.

• What are the benefits, pros, and cons of redux-thunk over redux-saga? https://hashnode.com/post/what-are-the-benefits-of-redux-thunk-over-redux-saga-what-pros-and-cons-do-they-have-over-each-other-ciqvyydh7065w3g53ffalif61
  An excellent discussion of where side effects belong in a Redux app, and how thunks and sagas can be used to handle async logic.

• Keeping Redux in check
  https://medium.com/@georgeleeme/keeping-redux-in-check-78534504b215
  Some tips on use of the Flux Standard Actions convention, and comparison of using redux-thunk vs redux-promise.

• "Argument: We should switch from thunks to sagas"
  http://en.arguman.org/we-should-switch-from-redux-thunk-to-redux-saga
  An debate flowchart with arguments for and against using thunks and sagas

• The Evolution of Redux Action Creators
  https://medium.com/@northerneyes/the-evolution-of-redux-action-creators-2973018bf2ae
  A comparison of ways to make action creation testable, looking at redux-thunk, a custom thunk-like middleware, and redux-saga

• What is the right way to do asynchronous operations in Redux?
  https://decembersoft.com/posts/what-is-the-right-way-to-do-asynchronous-operations-in-redux/
  An excellent look at the most popular libraries for Redux side effects, with comparisons of how each one works.

• Redux 4 Ways
  https://medium.com/react-native-training/redux-4-ways-95a130da0cdc
  Side-by-side comparisons of implementing some basic data fetching using thunks, sagas, observables, and a promise middleware

• 3 Common Approaches to Side-Effects in Redux
  https://goshakkk.name/redux-side-effect-approaches/
  An overview of what "side effects" are, how they relate to Redux, and the most common ways to handle side effects in a Redux app

• Redux: Thunk vs Saga
  http://blog.jakegardner.me/redux-thunk-vs-saga/
  A couple quick examples showing how to use thunks and sagas for the same task

• Redux Thunks Dispatching Other Thunks - Discussion and Best Practices
  https://medium.com/@talkol/redux-thunks-dispatching-other-thunks-discussion-and-best-practices-dd6c2b695ecf
  Some excellent thoughts on when it's okay to have a thunk dispatch another thunk, and other possible approaches.

• Redux-Observable Epics vs Redux Sagas
  https://shift.infinite.red/redux-observable-epics-vs-redux-sagas-8e53610c0eda
  A humorous look at how redux-observable and redux-saga compare. It recaps their backgrounds and basic ideas, then shows comparison implementations for some small tasks and rates the approaches.

• Async operations in React Redux applications
  https://codebrahma.com/structuring-async-operations-react-redux-applications/
  An introduction to the complexities of handling async logic in JS, and comparisons of how the same series of API calls could be handled using JS Promises, thunks, sagas, and observables.

• "Redux and API/fetch calls. How do you handle them?
  https://twitter.com/rem/status/888361414070501376
  A Twitter poll asking about people's preferences for handling async work in Redux. The replies are interesting, and show a very wide variety of choices being used.

• Understanding redux-saga: from action creators to sagas
  https://blog.logrocket.com/understanding-redux-saga-from-action-creators-to-sagas-2587298b5e71
  Some short examples comparing implementations of the same fetching logic inside a component, using redux-thunk, and using redux-saga.

• Polling with Redux
  https://bigbitecreative.com/polling-with-redux/
  Compares implementations of a polling loop between redux-saga and redux-observable

• Redux-Saga vs Redux-Observable
  https://hackmd.io/s/H1xLHUQ8e
  Some notes comparing sagas and observables, including "mental models", side-by-side comparison implementations of tasks like fetching / sequencing / cancelation, and more.

• Redux Sagas, Observables, oh my
  https://spectrum.chat/thread/2e738f7a-b385-4120-aff1-5fca9d1a6f34
  An extensive discussion thread that compares the relative uses cases and merits of redux-saga and redux-observable

Sagas

• Master Complex Redux Workflows with Sagas
  http://konkle.us/master-complex-redux-workflows-with-sagas/
  Describes what sagas are, how Redux-Saga uses generators to run sagas, some potential concerns, and how to use them.

• Stack Overflow: Why do we need middleware for async flux in Redux?
  http://stackoverflow.com/questions/34570758/why-do-we-need-middleware-for-async-flow-in-redux/34623840#34623840
  A comparison of imperative thunks vs declarative sagas, and some of the benefits that sagas can provide for testing and decoupling of logic.

• Managing Side Effects in React + Redux using Sagas
  http://jaysoo.ca/2016/01/03/managing-processes-in-redux-using-sagas/
  Demonstrates various ways to implement a Timer app as a state machine, including using sagas to manage the periodic updates.

• Persist Redux State By Using Sagas
  http://engineering.invisionapp.com/post/persist-redux-state-by-using-sagas/
  A very well-written set of examples showing how to use sagas to implement some complex store persistence logic.

• Handling async in Redux with Sagas
  http://wecodetheweb.com/2016/10/01/handling-async-in-redux-with-sagas/
  Covers the basic concepts and syntax of sagas, and how they can improve testability. (Updated version of a 2015 post, covering the latest version of redux-saga.)

• Redux Saga conceptual diagram
  https://twitter.com/kuy/status/731484272234663937
  A useful diagram illustrating the various things a saga can do

• "Redux Sagas benefits?"
  https://www.reddit.com/r/reactjs/comments/4ng8rr/redux_sagas_benefits/
  Discussion of when and why you might want to use sagas, with some great examples in the comments.

• Manage Side Effects Efficiently with Redux Saga
  https://youtu.be/QJVdcIlqGwc
  A presentation describing the concepts of generators and sagas.

• Redux Saga conceptual diagram
  https://qiita-image-store.s3.amazonaws.com/0/69860/8cc1a873-c675-9009-570d-9684da4a704f.png
  A nifty diagram from @kuy illustrating the general interaction of Redux Saga's async flow operators

• Async Operations using Redux-Saga
  https://medium.com/@andresmijares25/async-operations-using-redux-saga-2ba02ae077b3
  An example of using Redux-Saga to coordinate multiple async calls based on another article's flight data scenario.

• Should I use redux-saga or not?
  https://speakerdeck.com/kuy/should-i-use-redux-saga-or-not
  A presentation from Yuki Kodama, comparing side effect approaches. In Japanese, but still has a number of useful diagrams that can be understood by English speakers.

• Interview with Redux-Saga Author Yassine Eloaufi
  http://survivejs.com/blog/redux-saga-interview/
  An interview with the author of Redux-Saga, where he describes some of its concepts and history

• Lazy registration with Redux and Sagas
  http://goshakkk.name/lazy-auth-redux-saga-flow/
  Examples of using Redux-Saga to implement an async series of user interactions.

• A Saga that led Xero to Redux
  https://devblog.xero.com/a-saga-that-led-xero-to-redux-aa1361b9a800
  Examples of how Xero's async logic for their dashboard evolved over team, from nested callbacks to promises to Redux with sagas

• The Three 'R's: Refactoring, React, and Redux for robust async JS
  https://devblog.xero.com/the-three-rs-refactoring-react-and-redux-for-robust-async-js-252648a8632f
  More information from Xero on how they have used sagas for async workflows, including splitting code up into smaller sagas that can be composed.

• 4 Quick Tips for Managing Many Sagas in a React-Redux-Saga App
  https://decembersoft.com/posts/4-tips-for-managing-many-sagas-in-a-react-redux-saga-app/
  Some useful suggestions for structuring and organizing sagas

• Implementing feature flags using React and Redux Saga
  http://blog.launchdarkly.com/implementing-feature-flags-in-single-page-apps-using-react-and-redux-saga/
  A quick example of how to use sagas to manage feature flag API requests

• Javascript Power Tools: Redux-Saga
  http://formidable.com/blog/2017/javascript-power-tools-redux-saga/
  http://formidable.com/blog/2017/composition-patterns-in-redux-saga/
  http://formidable.com/blog/2017/real-world-redux-saga-patterns/
  A fantastic series that teaches the concepts, implementation, and benefits behind Redux-Saga, including how ES6 generators are used to control function flow, how sagas can be composed together to accomplish concurrency, and practical use cases for sagas.

• Managing Side Effects with Redux Saga: A Primer
  http://web.archive.org/web/20161112151214/https://www.sigient.com/blog/managing-side-effects-with-redux-saga-a-primer-1
  Looks at how side effects complicate testing, and how sagas use descriptions of side effects to make testing easier. Also looks at how sagas fit into a Redux application architecture.

• Exploring Redux Sagas
  https://medium.com/onfido-tech/exploring-redux-sagas-cc1fca2015ee
  An excellent article that explores how to use sagas to provide a glue layer to implement decoupled business logic in a Redux application.

• Redux-Saga: put() from inside a callback / File Upload Progress
  https://decembersoft.com/posts/redux-saga-put-from-inside-a-callback/
  https://decembersoft.com/posts/file-upload-progress-with-redux-saga/
  A pair of posts demonstrating how to use Redux-Saga's "event channel" feature to interact with non-Redux code

• Effects as Data
  https://gist.github.com/iammerrick/fc4a677cea11d9c896e8d3a29a184f91
  A small essay on the benefits of treating effects as data, and how it enables decoupling

• redux-saga factories and decorators
  https://medium.com/@TomasEhrlich/redux-saga-factories-and-decorators-8dd9ce074923
  Some quick examples of creating reusable sagas to reduce duplicate code

• Handling action errors in Redux-Saga using Either
  https://medium.com/@jamiedixon/handling-errors-in-redux-saga-using-either-12671bc6cf90
  Demonstrates an approach to handling error cases in Flux Standard Actions using the functional programming "Either" concept.

• Writing more testable code with Redux-Saga
  https://medium.com/grey-frogs/writing-more-testable-code-with-redux-saga-c1561f995225
  Gives examples of some sagas for managing complex async query handling logic, and how to use the redux-saga-test-plan library to help test their behavior.

• Analytics on easy mode with Redux-Saga
  https://goshakkk.name/analytics-easy-redux-saga/
  Quick examples of how to use Redux-Saga to implement analytics handling.

• Modelling common patterns with redux-saga
  https://medium.com/@chanakyabhardwaj/modelling-common-patterns-with-redux-saga-464a380a37ce
  Examples of saga logic patterns for behaviors like "first-amongst-these", "keep-doing-until", and "step-by-step".

• Building an event system using Redux and Sagas
  http://blog.servicebot.io/building-our-event-and-user-notification-system-in-express-using-redux-and-sagas/
  Some quick examples of using Redux-Saga in a Node Express app to handle processing for things like sending emails.

• Redux Saga Retry Patterns
  https://medium.com/@bryanfillmer/keep-trying-redux-saga-style-b273882b9ec
  https://codeburst.io/try-again-more-redux-saga-patterns-bfbc3ffcdc
  A pair of articles discussing ways to handle reconnects, retries, and error handling in sagas.

• Redux, Firebase, and the Saga in between
  https://medium.com/rumors/redux-firebase-and-the-saga-in-between-c2bd5adf6de1
  Discussion and examples of how to use sagas to simplify and generalize interaction with Firebase in a Redux app.

• When should I use a saga?
  https://medium.com/@felixclack/when-should-i-use-a-saga-708cb3c75e9a
  Some quick rules of thumb for determining if building a saga is a good choice for a given feature.

• Redux Saga: the Viking way to manage side effects
  https://www.slideshare.net/nachomartin/redux-sagas-react-alicante
  A comprehensive slideset that covers many aspects of sagas, from basic concepts to use with complex workflows.

• Detecting state changes with Redux-Saga
  https://goshakkk.name/detect-state-change-redux-saga/
  Shows a simple but useful technique for running saga behavior based on state changes rather than just dispatched actions.

• Common patterns with Redux-Saga
  https://engineering.universe.com/common-patterns-with-redux-saga-ed68f89dfecf
  Examples of useful patterns for sagas, including running multiple requests in parallel, using the race keyword to time out requests, and using sagas to manage a queue of events.

• States and React: step-by-step user interaction with state machines
  https://sandstorm.de/de/blog/post/states-and-react-step-by-step-user-interaction-with-state-machines.html
  Demonstrates managing "snackbar" popup notifications using sagas to show and hide the popups

• Taming Redux with Sagas
  https://objectpartners.com/2017/11/20/taming-redux-with-sagas/
  A good overview of Redux-Saga, including info on generator functions, use cases for sagas, using sagas to deal with promises, and testing sagas.

Observables

• Epic Middleware in Redux
  https://medium.com/@kevinsalter/epic-middleware-in-redux-e4385b6ff7c6
  Discussion and examples of using Redux-Observable and RxJS to create "epics" which can transform actions.

• Action Streams and Redux
  https://medium.com/@markusctz/action-streams-and-redux-77f8ac99c2e9
  Examples of how Redux-Observable can simplify complex async logic

• Using redux-observable to handle asynchronous logic in Redux
  https://medium.com/dailyjs/using-redux-observable-to-handle-asynchronous-logic-in-redux-d49194742522
  An extended post that compares a thunk-based implementation of handling a line-drawing example vs an observable-based implementation.

• Redux Observable to the rescue
  https://medium.com/@daslusan/redux-observable-to-the-rescue-b27f07406cf2
  A quick comparison of writing some complex AJAX-related logic as a thunk and with redux-observable, and some of the benefits of writing the code using observables.

• Using redux-observable for asynchronous actions
  https://medium.com/imersotechblog/using-redux-observable-for-asynchronous-actions-1afb31cbc01c
  Looks at possible complexities in handling async requests, and how redux-observable can be used to help handle complex async behavior.

• Reactive Redux State with RxJS
  https://ivanjov.com/reactive-redux-state-with-rxjs/
  Describes the concept of "Reactive PRogramming" and the RxJS library, and shows how to use redux-observable to fetch data, along with examples of testing.

Other Side Effect Approaches

• Better async Redux
  https://blog.scottnonnenberg.com/better-async-redux-i18n-and-node-js-versions/
  Comparisons and examples of using Redux-Loop for declarative side effects

• A simplified approach to calling APIs with Redux
  http://www.sohamkamani.com/blog/2016/06/05/redux-apis/
  A well-written example of creating a "data service" middleware that handles API requests, as well as examples of handling some request status state.

• Elm Architecture with Redux
  https://smallbusinessforum.co/elm-architecture-with-react-redux-redux-loop-645a67070b1a
  A short look at how Elm handles side effects, and how Redux-Loop can help implement a similar approach in Redux

• Redux-cycles
  http://nick.balestra.ch/talk/redux-cycles/#/0
  A slideshow that describes the basics of Cycle.js, and how the redux-cycles library can be used to handle side effects in Redux

• How to make your React app fully functional, fully reactive, and able to handle all those crazy side effects
  https://medium.freecodecamp.org/how-to-make-your-react-app-fully-functional-fully-reactive-and-able-to-handle-all-those-crazy-e5da8e7dac10
  A lengthy look at Cycle.js and the redux-cycles library, with plenty of diagrams to illustrate how it handles data flow.

• Testing for Race Conditions with Redux
  https://paulgray.net/race-conditions-in-redux/
  Examples of how to write reducer logic to handle multiple async responses that could return out of order.

• Building a React/Redux/Elm Bridge
  https://medium.com/javascript-inside/building-a-react-redux-elm-bridge-8f5b875a9b76
  Discusses various way to integrate React, Redux, and Elm together, including a Redux middleware that talks to Elm.

• Reacting to ProgressEvents with Redux
  https://medium.com/@andersonmcook/reacting-to-progressevents-with-redux-355ba021d336
  Demonstrates using the Redux-Logic library and RxJS to handle browser ProgressEvents