A simple way manage state in React, inspired by Clojure(Script) and reagent.cljs
react-atom?
react-atomin action
react-atomin CodeSandbox 🎮️
react-atomprovides a very simple way to manage state in React, for both global app state and for local component state: ✨
Atoms✨.
Atom:
import { Atom } from "@dbeining/react-atom";const appState = Atom.of({ color: "blue", userId: 1 });
deref
You can't inspect
Atomstate directly, you have to
dereference it, like this:
import { deref } from "@dbeining/react-atom";const { color } = deref(appState);
swap
You can't modify an
Atomdirectly. The main way to update state is with
swap. Here's its call signature:
function swap(atom: Atom, updateFn: (state: S) => S): void;
updateFnis applied to
atom's state and the return value is set as
atom's new state. There are just two simple rules for
updateFn:
To illustrate, here is how we might update
appState's color:
import { swap } from "@dbeining/react-atom";const setColor = color => swap(appState, state => ({ ...state, color: color }));
Take notice that our
updateFnis spreading the old state onto a new object before overriding
color. This is an easy way to obey the rules of
updateFn.
swap
You don't need to do anything special for managing side-effects. Just write your IO-related logic as per usual, and call
swapwhen 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 })); };
useAtom✨ custom React hook
useAtomis a custom React Hook. It does two things:
deref), and
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 onswap
*/} swap(appState, setRandomColor)}>Change Color
Nota Bene: You can also use a selector to subscribe to computed state by using the
options.selectargument. Read the docs for details.
react-atom?
`Atom.of`, `useAtom`, and `swap` will cover the vast majority of use cases.
Reducers? Actions? Thunks? Sagas? Nope, just `swap(atom, state => newState)`.
TheuseAtom
hook accepts an optionalselect
function that lets components subscribe to computed state. That means the component will only re-render when the value returned fromselect
changes.
React.useState
doesn't play nice with React.memo
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 thesetState
function in another function. That makes it hard to take advantage ofReact.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}"></expensivebutmemoized> > ); }
Every time
input
firesonChange
,ExpensiveButMemoized
has to re-render becausehandleDidComplete
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 => ({ ...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}"></expensivebutmemoized> > ); }
react-atom
is written in TypeScript so that every release is published with correct, high quality typings.
Hooks will makeclass
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-atomhas 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-atomalso has two
peerDependencies, namely,
[email protected]^16.8.0and
[email protected]^16.8.0, which contain the Hooks API.
react-atomAPI
@libre/atomAPI
react-atomin action
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 => ({
...state,
count: state.count + 1
}));
const decrement = () =>
swap(stateAtom, state => ({
...state,
count: state.count - 1
}));
const updateText = evt =>
swap(stateAtom, state => ({
...state,
text: evt.target.value
}));
const loadSomething = () =>
fetch("https://jsonplaceholder.typicode.com/todos/1")
.then(res => res.json())
.then(data => swap(stateAtom, state => ({ ...state, data })))
.catch(console.error);
//------------------------ COMPONENT ------------------------------//
export const App = () => {
const { count, data, text } = useAtom(stateAtom);
return (
<div>
<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>
</div>
);
};
ReactDOM.render(<app></app>, document.getElementById("root"));
react-atomin CodeSandbox 🎮️
You can play with
react-atomlive right away with no setup at the following links:
| JavaScript Sandbox | TypeScript Sandbox |
| ------------------------------- | ------------------------------- |
| |
|
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).