jotai/dist/vanilla/utils/atomWithDefault.js

👻 Primitive and flexible state management for React

import { atom } from '../../vanilla.js';
import { RESET } from './constants.js';
export function atomWithDefault(getDefault) {
    const EMPTY = Symbol();
    const overwrittenAtom = atom(EMPTY);
    if (process.env.NODE_ENV !== 'production') {
        overwrittenAtom.debugPrivate = true;
    }
    const anAtom = atom((get, options) => {
        const overwritten = get(overwrittenAtom);
        if (overwritten !== EMPTY) {
            return overwritten;
        }
        return getDefault(get, options);
    }, (get, set, update) => {
        const newValue = typeof update === 'function'
            ? update(get(anAtom))
            : update;
        set(overwrittenAtom, newValue === RESET ? EMPTY : newValue);
    });
    return anAtom;
}