xoid is a framework-agnostic state management library. X in its name signifies the inspiration it draws from great projects such as ReduX, MobX and Xstate. It was designed to be simple and scalable. It has extensive Typescript support.
xoid is lightweight (~1kB gzipped), but quite powerful. It's composed of building blocks for advanced state management patterns. One of the biggest aims of xoid is to unify global state, local component state, and finite state machines in a single API. While doing all these, it also aims to keep itself approachable for newcomers. More features are explained below, and the documentation website.
To install, run the following command:
npm install xoidor
yarn add xoidExamples
Quick Tutorial
xoid has only one export: create. Create is also exported as the default export.
import { create } from 'xoid'
import create from 'xoid'
Atom
Atoms are holders of state.
import { create } from 'xoid'
const atom = create(3)
console.log(atom.value) // 3
atom.set(5)
atom.update((state) => state + 1)
console.log(atom.value) // 6Atoms can have actions if the second argument is used.
import { create } from 'xoid'
const numberAtom = create(5, (atom) => ({
increment: () => atom.update(s => s + 1),
decrement: () => atom.update(s => s - 1)
}))
numberAtom.actions.increment()There's the .focus method, which can be used as a selector/lens. xoid is based on immutable updates, so if you "surgically" set state of a focused branch, changes will propagate to the root.
import { create } from 'xoid'
const atom = create({ deeply: { nested: { alpha: 5 } } })
const previousValue = atom.value
// select `.deeply.nested.alpha`
const alphaAtom = atom.focus(s => s.deeply.nested.alpha)
alphaAtom.set(6)
// root state is replaced with new immutable state
assert(atom.value !== previousValue) // ✅
assert(atom.value.deeply.nested.alpha === 6) // ✅Derived state
Atoms can be derived from other atoms. This API was heavily inspired by Recoil.
const alpha = create(3)
const beta = create(5)
// derived atom
const sum = create((get) => get(alpha) + get(beta))Alternatively, .map method can be used to quickly derive the state from a single atom.
const alpha = create(3)
// derived atom
const doubleAlpha = alpha.map((s) => s * 2)Subscriptions
For subscriptions, subscribe and watch are used. They are the same, except watch runs the callback immediately, while subscribe waits for the first update after subscription.
const unsub = atom.subscribe(
(state, previousState) => { console.log(state, previousState) }
)
// later
unsub()To cleanup side-effects, a function can be returned in the subscriber function. (Just like
React.useEffect)
React integration
@xoid/react is based on two hooks. useAtom subscribes the component to an atom. If a second argument is supplied, it'll be used as a selector function.
import { useAtom } from '@xoid/react'
// in a React component
const state = useAtom(atom)The other hook is useSetup. It can be used for creating local component state. It's similar to React.useMemo with empty dependencies array. It'll run its callback only once.
import { useSetup } from '@xoid/react'
const App = () => {
const $counter = useSetup(() => create(5))
...
}
useSetupis guaranteed to be non-render-causing. Atoms returned by that should be explicitly subscribed viauseAtomhook.
An outer value can be supplied as the second argument. It'll turn into a reactive atom.
import { useSetup } from '@xoid/react'
const App = (props: Props) => {
const setup = useSetup(($props) => {
// `$props` has the type: Atom<Props>
// this way, we can react to `props.something` as it changes
$props.focus(s => s.something).subscribe(console.log)
}, props)
...
}If you've read until here, you have enough knowledge to start using xoid. You can refer to the documentation website for more.
More features
Pattern: Finite state machines
No additional syntax is required for state machines. Just use the good old create function.
import { create } from 'xoid'
import { useAtom } from '@xoid/react'
const createMachine = () => {
const red = { color: '#f00', onClick: () => atom.set(green) }
const green = { color: '#0f0', onClick: () => atom.set(red) }
const atom = create(red)
return atom
}
// in a React component
const { color, onClick } = useAtom(createMachine)
return <div style={{ color }} onClick={onClick} />Redux Devtools integration
Import @xoid/devtools and set a debugValue to your atom. It will send values to the Redux Devtools Extension.
import { devtools } from '@xoid/devtools'
import { create, use } from 'xoid'
devtools() // run once
const atom = create(
{ alpha: 5 },
(atom) => {
const $alpha = atom.focus(s => s.alpha)
return {
inc: () => $alpha.update(s => s + 1),
resetState: () => atom.set({ alpha: 5 })
deeply: {
nested: {
action: () => $alpha.set(5)
}
}
}
}
)
atom.debugValue = 'myAtom' // enable watching it by the devtools
const { deeply, incrementAlpha } = atom.actions // destructuring is no problem
incrementAlpha() // logs "(myAtom).incrementAlpha"
deeply.nested.action() // logs "(myAtom).deeply.nested.action"
atom.focus(s => s.alpha).set(25) // logs "(myAtom) Update ([timestamp])Why xoid?
- Easy to learn
- Small bundle size
- Framework-agnostic
- Extensive Typescript support
- Easy to work with nested states
- Computed values, transient updates
- Can be used to express finite state machines
- No middleware is required for async/generator stuff
- Global state and local component state in the same API
Other packages
@xoid/react- React integration@xoid/devtools- Redux Devtools integration@xoid/lite- Lighter version with less features@xoid/feature- A typesafe plugin system oriented in ES6 classes
Thanks
Following awesome projects inspired xoid a lot.