State management made simple for React. Built on React Hooks. Inspired by `atom`s in `reagent.cljs`.

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147264.1.21a year ago4 years agoMinified + gzip package size for @dbeining/react-atom in KB


  alt="react-atom logo" />

A simple way to manage shared state in React

Built on the React Hooks API

Inspired by atoms in reagent.cljs

TypeScript npm (scoped) npm bundle size (minified) npm bundle size (minified + gzip)
Build Status codecov npm
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react-atom provides a very simple way to manage state in React, for both global app state and for local component state: āœØAtomsāœØ.

Put your state in an Atom:

import { Atom } from "@dbeining/react-atom";

const appState = Atom.of({
  color: "blue",
  userId: 1

Read state with deref

You can't inspect Atom state directly, you have to dereference it, like this:
import { deref } from "@dbeining/react-atom";

const { color } = deref(appState);

Update state with swap

You can't modify an Atom directly. The main way to update state is with swap. Here's its call signature:
function swap<S>(atom: Atom<S>, updateFn: (state: S) => S): void;

updateFn is applied to atom's state and the return value is set as atom's new state. There are just two simple rules for updateFn:
  1. it must return a value of the same type/interface as the previous state
  2. it must not mutate the previous state

To illustrate, here is how we might update appState's color:
import { swap } from "@dbeining/react-atom";

const setColor = color =>
  swap(appState, state => ({
    color: color

Take notice that our updateFn is spreading the old state onto a new object before overriding color. This is an easy way to obey the rules of updateFn.

Side-Effects? Just use swap

You don't need to do anything special for managing side-effects. Just write your IO-related logic as per usual, and call swap when you've got what you need. For example:
const saveColor = async color => {
  const { userId } = deref(appState);
  const theme = await post(`/api/user/${userId}/theme`, { color });
  swap(appState, state => ({ ...state, color: theme.color }));

Re-render components on state change with the āœØuseAtomāœØ custom React hook

useAtom is a custom React Hookcustomhooksurl. It does two things:
  1. returns the current state of an atom (like deref), and
  2. subscribes your component to the atom so that it re-renders every time its state changes

It looks like this:
export function ColorReporter(props) {
  const { color, userId } = useAtom(appState);

  return (
        User {userId} has selected {color}
      {/* `useAtom` hook will trigger a re-render on `swap` */}
      <button onClick={() => swap(appState, setRandomColor)}>Change Color</button>

Nota Bene: You can also use a selector to subscribe to computed state by using the options.select argument. Read the docs for details.

Why use react-atom?

šŸ˜Œ <strong>Tiny API / learning curve</strong>
`Atom.of`, `useAtom`, and `swap` will cover the vast majority of use cases.
šŸš« <strong>No boilerplate, just predictable state management</strong>   
Reducers? Actions? Thunks? Sagas? Nope, just `swap(atom, state => newState)`. 
šŸŽµ <strong>Tuned for performant component rendering</strong>   
The useAtom hook accepts an optional select function that lets components subscribe to computed state. That means the component will only re-render when the value returned from select changes.
šŸ˜¬ <strong><code>React.useState</code> doesn't play nice with <code>React.memo</code></strong>
useState is cool until you realize that in most cases it forces you to pass new function instances through props on every render because you usually need to wrap the setState function in another function. That makes it hard to take advantage of React.memo. For example:

function Awkwardddd(props) {
  const [name, setName] = useState("");
  const [bigState, setBigState] = useState({ ...useYourImagination });

  const updateName = evt => setName(evt.target.value);
  const handleDidComplete = val => setBigState({ ...bigState, inner: val });

  return (
      <input type="text" value={name} onChange={updateName} />
      <ExpensiveButMemoized data={bigState} onComplete={handleDidComplete} />

Every time input fires onChange, ExpensiveButMemoized has to re-render because handleDidComplete is not strictly equal (===) to the last instance passed down.
The React docs admit this is awkward and suggest using Context to work around it, because the alternative is super convoluted.
With react-atom, this problem doesn't even exist. You can define your update functions outside the component so they are referentially stable across renders.
const state = Atom.of({ name, bigState: { ...useYourImagination } });

const updateName = ({ target }) => swap(state, prev => ({ ...prev, name: target.value }));

const handleDidComplete = val =>
  swap(state, prev => ({
    bigState: { ...prev.bigState, inner: val }

function SoSmoooooth(props) {
  const { name, bigState } = useAtom(state);

  return (
      <input type="text" value={name} onChange={updateName} />
      <ExpensiveButMemoized data={bigState} onComplete={handleDidComplete} />

<span style="background:#00a1f1;color:white;font-weight:500;padding:1px 0px;">TS</span> <strong>First-class TypeScript support</strong>   
react-atom is written in TypeScript so that every release is published with correct, high quality typings.
šŸ‘£ Tiny footprint
  alt="react-atom minified file size"/>

  alt="react-atom minified+gzipped file size"/>
āš›ļø <strong>Embraces React's future with Hooks</strong>   
Hooks will make class components and their kind (higher-order components, render-prop components, and function-as-child components) obsolete. react-atom makes it easy to manage shared state with just function components and hooks.


npm i -S @dbeining/react-atom


react-atom has one bundled dependency, @libre/atom, which provides the Atom data type. It is re-exported in its entirety from @dbeining/atom. You may want to reference the docs here.
react-atom also has two peerDependencies, namely, react@^16.8.0 and react-dom@^16.8.0, which contain the Hooks API.


react-atom API
@libre/atom API

Code Example: react-atom in action

Click for code sample 

import React from "react";
import ReactDOM from "react-dom";
import { Atom, useAtom, swap } from "@dbeining/react-atom";

//------------------------ APP STATE ------------------------------//

const stateAtom = Atom.of({
  count: 0,
  text: "",
  data: {
    // ...just imagine

//------------------------ EFFECTS ------------------------------//

const increment = () =>
  swap(stateAtom, state => ({
    count: state.count + 1

const decrement = () =>
  swap(stateAtom, state => ({
    count: state.count - 1

const updateText = evt =>
  swap(stateAtom, state => ({
    text: evt.target.value

const loadSomething = () =>
    .then(res => res.json())
    .then(data => swap(stateAtom, state => ({ ...state, data })))

//------------------------ COMPONENT ------------------------------//

export const App = () => {
  const { count, data, text } = useAtom(stateAtom);

  return (
      <p>Count: {count}</p>
      <p>Text: {text}</p>

      <button onClick={increment}>Moar</button>
      <button onClick={decrement}>Less</button>
      <button onClick={loadSomething}>Load Data</button>
      <input type="text" onChange={updateText} value={text} />

      <p>{JSON.stringify(data, null, "  ")}</p>

ReactDOM.render(<App />, document.getElementById("root"));

šŸ•¹ļø Play with react-atom in CodeSandbox šŸŽ®ļø

You can play with react-atom live right away with no setup at the following links:
| JavaScript Sandbox | TypeScript Sandbox | | ------------------------------- | ------------------------------- | | !try react-atomimgurljs | !try react-atomimgurlts |

Contributing / Feedback

Please open an issue if you have any questions, suggestions for improvements/features, or want to submit a PR for a bug-fix (please include tests if applicable).