30秒学会 React 片段 – React useSet hook

Creates a stateful Set object, and a set of functions to manipulate it.

• Use the useState() hook and the Set constructor to create a new Set from the initialValue.
• Use the useMemo() hook to create a set of non-mutating actions that manipulate the set state variable, using the state setter to create a new Set every time.
• Return the set state variable and the created actions.

代码实现

const useSet = initialValue => {
  const [set, setSet] = React.useState(new Set(initialValue));

  const actions = React.useMemo(
    () => ({
      add: item => setSet(prevSet => new Set([...prevSet, item])),
      remove: item =>
        setSet(prevSet => new Set([...prevSet].filter(i => i !== item))),
      clear: () => setSet(new Set()),
    }),
    [setSet]
  );

  return [set, actions];
};

使用样例

const MyApp = () => {
  const [set, { add, remove, clear }] = useSet(new Set(['apples']));

  return (
    <div>
      <button onClick={() => add(String(Date.now()))}>Add</button>
      <button onClick={() => clear()}>Reset</button>
      <button onClick={() => remove('apples')} disabled={!set.has('apples')}>
        Remove apples
      </button>
      <pre>{JSON.stringify([...set], null, 2)}</pre>
    </div>
  );
};

ReactDOM.createRoot(document.getElementById('root')).render(
  <MyApp />
);

翻译自：https://www.30secondsofcode.org/react/s/use-set