Discount store

Store data globally in your app. Generic library, no dependencies.

Installation

npm install discount-store

import { createStore } from 'discount-store'

Usage

Creating a store

const initialState = {}
createStore(initialState)

NOTE: Since we observe each field in the store for changes, and we have chosen to support IE11 for now, we cannot use Proxy. Therefore, we must know all the fields that will be defined at the time the store is created. If you try to set a field that did not exist upon creation, it will throw an error.

const { state } = createStore({ count: 0 })
state.foo = 'bar' // TypeError: Cannot add property foo, object is not extensible

Getting store values

You can get a store value either from the get method, or by accessing the field directly from the state object.

const { state, get } = createStore({ count: 0 })
get('count') // 0
state.count // 0

Setting store values

You can set a store value either from the set method, or by directly setting the field on the state object.

const { state, set } = createStore({ count: 0 })
state.count += 1 // 1
set('count', 5) // 5

Listening for state changes to fields

You can subscribe to a field to execute a callback any time that field changes by using the onChange method. This includes when a field is changed from a reset or clear.

const { state, onChange } = createStore({ count: 0 })
onChange('count', newValue => {
    // do some stuff
});
state.count += 1;

Unsubsribing to state changes

The method onChange returns a function, that when invoked, will the unsubsribe callback from those change events.

const { state, onChange } = createStore({ count: 0 })
const offChange = onChange('count', newValue => {
    // do some stuff
    offChange() // effectively a 'once'
});
state.count += 1;

Listening for any state events

With the on method, there are four events that you can subscribe to for the store: set, get, clear, reset

const { state, on } = createStore({ count: 0 })
on('set', (key, value) => {})
on('get', value => {})
on('clear', () => {})
on('reset', () => {})

Unsubscribing from state events

The on method returns a method that, when invoked, unsubsribes the callback from that event.

const { state, on } = createStore({ count: 0 })
const offSet = on('set', (key, value) => {
    offSet() // effectively a 'once'
})

Setting event listeners in bulk

With the use method, you can set an event listener for each of the store events: set, get, clear, reset

const { use } = createStore({ count: 0 })
use({
    get: value => {},
    set: (key, value) => {},
    reset: () => {},
    clear: () => {}
})

Clearing the store

Clearing the store empties it of all it's values. However, the keys are kept.

const { state, clear } = createStore({ count: 0 })
state.count // 0
clear()
state.count // undefined

Reseting the store

Reseting the store resets the state back to what it was initially created with.

const { state, reset } = createStore({ count: 0 })
state.count += 1 // 1
reset()
state.count // 0

Inspiration

This package's API is mostly inspired by @stencil/store with a few exceptions. I've excluded dispose, added clear, removed any peer dependencies, and kept support for IE11. Their API is simple and great, but I wanted an option for a store that was not tied to any framework or library (Stencil, Svelte, React, Redux) or design pattern (Flux).