new util useAtomCallback

[dai-shi]

close #60

• impl
• examples
• docs

---

Examples

import * as React from "react";
import { useEffect, useState, useCallback } from "react";
import { Provider, atom, useAtom } from "jotai";
import { useAtomCallback } from "jotai/utils";
import "./styles.css";

const countAtom = atom(0);

const Counter = () => {
  const [count, setCount] = useAtom(countAtom);
  return (
    <>
      {count} <button onClick={() => setCount((c) => c + 1)}>+1</button>
    </>
  );
};

const Monitor = () => {
  const [count, setCount] = useState(0);
  const readCount = useAtomCallback(
    useCallback((get) => {
      const currCount = get(countAtom);
      setCount(currCount);
      return currCount;
    }, [])
  );
  useEffect(() => {
    const timer = setInterval(async () => {
      console.log(await readCount());
    }, 1000);
    return () => {
      clearInterval(timer);
    };
  }, [readCount]);
  return <div>current count: {count}</div>;
};

const App = () => (
  <Provider>
    <div className="App">
      <h1>Hello CodeSandbox</h1>
      <h2>Start editing to see some magic happen!</h2>
      <Counter />
      <Monitor />
    </div>
  </Provider>
);

export default App;

https://codesandbox.io/s/react-typescript-forked-6ur43?file=/src/App.tsx

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 82bed93:

Sandbox	Source
React	Configuration
React Typescript	Configuration
React Typescript (forked)	PR

[dai-shi]

I look forward to someone working on better examples, docs and tests.