38 lines
1.1 KiB
TypeScript
38 lines
1.1 KiB
TypeScript
import { Dispatch, SetStateAction, useState } from "react";
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// like useState, but it is persisted in localStorage
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// important: values must be JSON-(de-)serializable
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export function usePersistentState<T>(key: string, initial: T): [T, Dispatch<SetStateAction<T>>] {
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const [state, setState] = useState(() => {
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const recovered = localStorage.getItem(key);
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let parsed;
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if (recovered !== null) {
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try {
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parsed = JSON.parse(recovered);
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return parsed;
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} catch (e) {
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// console.warn(`failed to recover state for option '${key}'`, e,
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// '(this is normal when running the app for the first time)');
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}
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}
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return initial;
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});
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function setStateWrapped(val: SetStateAction<T>) {
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setState((oldState: T) => {
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let newVal;
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if (typeof val === 'function') {
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// @ts-ignore: i don't understand why 'val' might not be callable
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newVal = val(oldState);
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}
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else {
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newVal = val;
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}
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const serialized = JSON.stringify(newVal);
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localStorage.setItem(key, serialized);
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return newVal;
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});
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}
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return [state, setStateWrapped];
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}
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