Most.js based middleware for Redux.
Handle async actions with monadic streams & reactive programming.
With yarn (recommended):
yarn add redux-mostor with npm:
npm install --save redux-mostAdditionally, make sure the peer dependencies, redux and most, are also installed.
redux-most is based on redux-observable.
It uses the same pattern/concept of "epics"
without requiring RxJS 5 as a peer dependency.
Although redux-observable does provide capability for using other stream libraries via adapters,
redux-most allows you to bypass needing to install both RxJS 5 and most. I prefer most for
working with observables and would rather have minimal dependencies. So, I wrote
this middleware primarily for my own use.
Please, see redux-observable's documentation
for details on usage.
RxJS 5 is great. It's quite a bit faster than RxJS 4, and Rx, in general, is a
very useful tool which happens to exist across many different languages.
Learning it is definitely a good idea. However, most is significantly smaller,
less complicated, and faster than RxJS 5. I prefer its more minimal set of
operators and its focus on performance. Also, like Ramda
or lodash/fp, most
supports a functional API in which the data collection (a stream, rather than
an array, in this case) gets passed in last. This is important, because it
allows you to use functional programming techniques like currying & partial
application, which you can't do with RxJS without writing your own wrapper
functions, because it only offers an OOP/fluent/chaining style API.
It's true that it's quite easy to implement the core ideas of Redux with
observables using the scan operator. (See my inferno-most-fp-demo
for an example.) However, the Redux DevTools
provide what is arguably the nicest developer tooling experience currently available
in the JavaScript ecosystem. Therefore, it is huge to be able to maintain it as an asset
while still reaping the benefits of reactive programming with streams. Purists, those who
are very experienced with working with observables, and those working on smaller apps
may not care as much about taking advantage of that tooling as using an elegant
streams-only based solution, and that's fine. The important thing is having a choice.
Why redux-most or redux-observable over redux-saga?
redux-saga is nice. It's a sophisticated approach to handling asynchronous
actions with Redux and can handle very complicated tasks with ease. However,
due to generators being pull-based, it is much more imperative in nature. I
simply prefer the more declarative style of push-based streams & reactive
programming.
I chose not to extend the Observable/Stream type with a custom ActionsObservable
type. So, when working with redux-most, you will be working with normal most
streams without any special extension methods. However, I have offered something
similar to redux-observable's ofType operator in redux-most with the
select helper function.
Like ofType, select is a convenience utility for filtering
actions by a specific type. However, ofType can optionally take multiple
action types to filter on, whereas select only takes a single type. I am not
yet convinced of a great use case for filtering on multiple types. If you have
one, please open an issue and describe it to me.
Additionally, to better align with the most API, select can be used in either
a fluent style or a more functional style.
To use the fluent style, just use most's thru operator to pass the stream
through to select as the 2nd argument.
action$.thru(select(ActionTypes.SEARCHED_USERS_DEBOUNCED))Otherwise, simply directly pass the stream as the 2nd argument.
select(ActionTypes.SEARCHED_USERS_DEBOUNCED, action$)createEpicMiddleware(rootEpic) is used to create an instance of the actual redux-most middleware.
You provide a single, root Epic.
Arguments
rootEpic(Epic): The root Epic.
Returns
(MiddlewareAPI): An instance of the redux-most middleware.
Example
// redux/configureStore.js
import { createStore, applyMiddleware, compose } from 'redux'
import { createEpicMiddleware } from 'redux-most'
import { rootEpic, rootReducer } from './modules/root'
const epicMiddleware = createEpicMiddleware(rootEpic)
export default function configureStore() {
const store = createStore(
rootReducer,
applyMiddleware(epicMiddleware)
)
return store
}combineEpics(), as the name suggests, allows you to take multiple epics and combine them into a single one.
Arguments
...epics(Epic[]): The epics to combine.
Returns
(Epic): An Epic that merges the output of every Epic provided and passes along the redux store as arguments.
Example
// epics/index.js
import { combineEpics } from 'redux-most'
import pingEpic from './ping'
import fetchUserEpic from './fetchUser'
export default combineEpics(
pingEpic,
fetchUserEpic
)An instance of the redux-most middleware.
To create it, pass your root Epic to createEpicMiddleware.
Methods
Replaces the epic currently used by the middleware.
It is an advanced API. You might need this if your app implements code splitting and you want to load some of the epics dynamically or you're using hot reloading.
Arguments
nextEpic(Epic): The next epic for the middleware to use.
A helper function for filtering the stream of actions by type.
Arguments
actionType(String): The type of action you want to filter by.stream(Stream): The stream of actions you are filtering. Ex:actions$.
The select operator is curried, allowing you to use a fluent or functional style.
Examples
// fluent style
import * as ActionTypes from '../ActionTypes'
import { clearSearchResults } from '../actions'
import { select } from 'redux-most'
const clear = action$ =>
action$.thru(select(ActionTypes.SEARCHED_USERS_DEBOUNCED))
.filter(action => !action.payload.query)
.map(clearSearchResults)
export default clear// functional style
import * as ActionTypes from '../ActionTypes'
import { clearSearchResults } from '../actions'
import { select } from 'redux-most'
const clear = action$ => {
const search$ = select(ActionTypes.SEARCHED_USERS_DEBOUNCED, action$)
const emptySearch$ = filter(action => !action.payload.query, search$)
return map(clearSearchResults, emptySearch$)
}
export default clear