observable-state-store

Simple observable state store.

Features

• Clear state definitions
• Clear action definitions
• Observable
• Simple to use and maintain

Installation

npm i --save observable-state-store

Usage

import Store from 'observable-state-store'

// define state
const state = {
  count: 0
}

// define actions
const actions = {
  inc: (state, number) => Object.assign({}, state, {count: state.count + number})
}

// create store
const store = new Store({state, actions})

// subscribe to the state
const subscription = store.subscribe((newState, oldState) => {
  if (newState.count > oldState.count) {
    console.log('count inc!')
  }
});

// execute action
store.actions.inc(-2); // nothing
store.actions.inc(3); // print 'count inc!'

// stop subscription
subscription.stop();
store.actions.inc(2); // nothing 

APIs

Store

constructor(options)

options is an object with fields

• state
• actions

state can be anything, but we recommend to use Immutable.js or similar things as your state.

actions are functions grouped into an object. The signature of any action is

function(oldState, ...args): newState

Inside the action body, you should not modify the old state directly. Instead, you should create and return an new state.

subscribe(observer): subscription

Subscribe to the store, and get notified by any execution of the actions.

observer is an function with the signature

function(newState, oldState)

You should not modify either newState or oldState.

Call subscription.stop() to stop the subscription.

actions

actions are mapped from the actions you passed into the constructor with new signature

function(...args)

For example, if you passed into constructor such an action

{
  inc: (state, number) => Object.assign({}, state, {count: state.count + number})
}

then you can call the corresponding version of action on the store this way

store.actions.inc(3)

getState(): state

Get current state directly. You should not modify the state it returns.

License

MIT