User {userId} has selected {color}
{/* `useAtom` hook will trigger a re-render on `swap` */}`Atom.of`, `useAtom`, and `swap` will cover the vast majority of use cases.
Reducers? Actions? Thunks? Sagas? Nope, just `swap(atom, state => newState)`.
TheuseAtomhook accepts an optionalselectfunction that lets components subscribe to computed state. That means the component will only re-render when the value returned fromselectchanges.
React.useState doesn't play nice with React.memo
useStateis 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 thesetStatefunction in another function. That makes it hard to take advantage ofReact.memo. For example:---```jsx 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 ( <>); } ``` 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](https://reactjs.org/docs/hooks-faq.html#how-to-avoid-passing-callbacks-down), because [the alternative is super convoluted](https://reactjs.org/docs/hooks-faq.html#how-to-read-an-often-changing-value-from-usecallback). 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. ```jsx const state = Atom.of({ name, bigState: { ...useYourImagination } }); const updateName = ({ target }) => swap(state, prev => ({ ...prev, name: target.value })); const handleDidComplete = val => swap(state, prev => ({ ...prev, bigState: { ...prev.bigState, inner: val } })); function SoSmoooooth(props) { const { name, bigState } = useAtom(state); return ( <> ); } ```
react-atom is written in TypeScript so that every release is published with correct, high quality typings.
Hooks will makeclasscomponents and their kind (higher-order components, render-prop components, and function-as-child components) obsolete.react-atommakes it easy to manage shared state with just function components and hooks.
Count: {count}
Text: {text}
{JSON.stringify(data, null, " ")}