xstream-store

xstream-store

A redux-like store module for xstream inspired by redux.

Take the pain out of handling side-effects with the power of observables. Eliminate the need for use of middleware such as redux-thunk, and side-effect handlers such as redux-saga.

Install

$ npm i xstream-store xstream

Example

View the source in examples/:

$ node examples/counter

Usage

// my-streamed-counter.js

const ADD_TYPE = 'add';
const addActionCreator = value => ({
  type: ADD_TYPE,
  value,
});

const RESET_TYPE = 'reset';
const resetAction = {
  type: RESET_TYPE,
};

const initialState = {value: 0};

const counter$Creator = select =>
  // our counter stream that only receives `counter` state
  xs
    .merge(
      select(ADD_TYPE).map(action => state => ({
        ...state,
        value: state.value + action.value,
      })),
      select(RESET).map(_ => _ => initialState)
    )
    // provide initialState in a callback
    .startWith(() => initialState);

const counterEffectsCreator = (select, dispatch) => {
  // a stream of all actions
  const action$ = select();
  // a stream of add actions
  const addAction$ = select(ADD_TYPE);
  // a stream of reset actions
  const reset$ = select(RESET_TYPE);

  action$.addListener({
    next(action) {
      console.log('I log on every action', action);
    }
  })

  add$.addListener({
    next(action) {
      console.log('I log every add action', action);

      // dispatch a reset when our counter's value is greater than 3
      if (action.value > 3) {
        dispatch(resetAction);
      }
    }
  })

  reset$.addListener({
    next() {
      console.log('Counter reset!');
    }
  })
};

export {
  addAction,
  counter$Creator,
  counterEffectsCreator,
}

// store.js
import createStore from 'xstream-store';
import {
  addActionCreator,
  counterEffectsCreator,
  counterStreamCreators
} from './my-streamed-counter'

const add1Action = addActionCreator(1);

const streamCreatorMap = {
  counter: counterStreamCreator,
}

const effectCreators = [
  counterEffectsCreator,
  // fooEffectsCreator
];

const store = createStore(streamCreatorMap, effectCreators);

// subscribe to your state stream
store.state$.addListener({
  next(state) { console.log(`entire state: ${state}`) },
});

const counterState = store.state$
                      .map(({counter}) => counter)
                      .addListener({
                        next(counterState) {
                          console.log(`counter state: ${state}`)
                        }
                      });

// dispatch actions
store.dispatch(add1Action);
// entire state: {counter: { value: 1 }}
// counter state: { value: 1 }

store.dispatch(add1Action);
// entire state: {counter: { value: 2 }}
// counter state: { value: 2 }

createStore

xstream-store exports a single function, createStore. createStore returns an object containing the initial state of the store, a stream of the current state, and a dispatch function for updating values in the store

const streamCreatorMap = {
  counter: myCounterStreamCeator
};

const effectCreators = [
  myCounterEffectCreator
];

const {dispatch, state$, initialState} = createStore(streamCreatorMap, effectCreators);

Parameter	Type	Required	Description
streamCreatorMap	obj: { [name]: streamCreator, }	true	An object mapping each streamCreator to a key on the store
effectCreators	[effectCreator]	false	An array of effect creators. xstream-store will map over each effect creator, passing in a select function for filtering actions within the effect creator, and a dispatch action for dispatching actions from within the effect creator

state$

The state stream returned by createStore. Create subscribers to state$ to respond to changes to state:

state$.map(({counter}) => counter)
      .subscribe({
        next(counter) {
          // do something with latest counter value
        }
      });

dispatch

Dispatch actions to update the state of your store:

const incrementAction = {type: 'increment'}
const addActionCreator = n => ({
  type: 'add',
  value: n,
});

// increment counter value
dispatch(incrementAction);

// add 5 to counter value
dispatch(addActionCreator(5))

initialState

The initial state of the entire store, as defined by the initial state of each stream creator.

Actions

Stream Creator

select

Effects Creator

select

dispatch

Related Libraries

• xstream-store-resource - easily generate streams for asynchronous requests
• react-xstream-store - connect React components to an xstream store

Todo

• add usage

License

MIT