import { useEffect, useState } from "react"; type SetValue = T | ((val: T) => T); function useLocalStorage( key: string, initialValue: T, ): [T, (value: SetValue) => void] { // State to store our value // Pass initial state function to useState so logic is only executed once const [storedValue, setStoredValue] = useState(() => { try { // Get from local storage by key const item = window.localStorage.getItem(key); // Parse stored json or if none return initialValue return item ? JSON.parse(item) : initialValue; } catch (error) { // If error also return initialValue console.log(error); return initialValue; } }); // useEffect to update local storage when the state changes useEffect(() => { try { // Allow value to be a function so we have same API as useState const valueToStore = typeof storedValue === "function" ? storedValue(storedValue) : storedValue; // Save state window.localStorage.setItem(key, JSON.stringify(valueToStore)); } catch (error) { // A more advanced implementation would handle the error case console.log(error); } }, [key, storedValue]); return [storedValue, setStoredValue]; } export default useLocalStorage;