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備忘録: TypescriptでのRecoilとLocalStorage接続

recoiljs.org

const localStorageEffect =
  <T>(key: string): AtomEffect<T> =>
  ({setSelf, onSet}) => {
    if (process.browser) {
      const savedValue = localStorage.getItem(key);
      if (savedValue !== null) {
        setSelf(JSON.parse(savedValue));
      }

      onSet((newValue, _, isReset) => {
        isReset
          ? localStorage.removeItem(key)
          : localStorage.setItem(key, JSON.stringify(newValue));
      });
    }
  };

使用例

export const DebugModeState = atom({
  key: 'DebugModeState',
  default: false,
  effects: [localStorageEffect<boolean>('debug_mode')],
});