JAVASCRIPT
How to persist React state with useLocalStorage hook
Build a custom React useLocalStorage hook to effortlessly store and retrieve component state from the browser's localStorage, maintaining data across sessions.
import { useState, useEffect } from 'react';
function useLocalStorage(key, initialValue) {
const [storedValue, setStoredValue] = useState(() => {
try {
const item = window.localStorage.getItem(key);
return item ? JSON.parse(item) : initialValue;
} catch (error) {
console.error(error);
return initialValue;
}
});
useEffect(() => {
try {
window.localStorage.setItem(key, JSON.stringify(storedValue));
} catch (error) {
console.error(error);
}
}, [key, storedValue]);
return [storedValue, setStoredValue];
}
// Example Usage:
// function ThemeSwitcher() {
// const [theme, setTheme] = useLocalStorage('app-theme', 'light');
//
// const toggleTheme = () => {
// setTheme(theme === 'light' ? 'dark' : 'light');
// };
//
// return (
// <button onClick={toggleTheme}>Toggle Theme: {theme}</button>
// );
// }
How it works: The useLocalStorage hook initializes state by attempting to retrieve a value from localStorage, falling back to an initial value if none is found or an error occurs. A useEffect hook then synchronizes changes to the state with localStorage, ensuring data persistence across page reloads and browser sessions.