JAVASCRIPT

Persist React State with a useLocalStorage Hook

Create a custom React hook, useLocalStorage, to automatically synchronize component state with the browser's local storage, ensuring data persistence.

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.log(error);
      return initialValue;
    }
  });

  useEffect(() => {
    try {
      window.localStorage.setItem(key, JSON.stringify(storedValue));
    } catch (error) {
      console.log(error);
    }
  }, [key, storedValue]);

  return [storedValue, setStoredValue];
}

// Example Usage:
// function UserSettings() {
//   const [theme, setTheme] = useLocalStorage('appTheme', 'dark');
//   const [fontSize, setFontSize] = useLocalStorage('appFontSize', 16);

//   return (
//     <div>
//       <p>Current Theme: {theme}</p>
//       <button onClick={() => setTheme(theme === 'dark' ? 'light' : 'dark')}>Toggle Theme</button>
//       <p>Font Size: {fontSize}px</p>
//       <button onClick={() => setFontSize(fontSize + 1)}>Increase Font</button>
//     </div>
//   );
// }

How it works: The `useLocalStorage` hook allows you to store and retrieve component state from the browser's local storage, making it persistent across page reloads. It initializes state by attempting to parse a value from local storage, falling back to an `initialValue` if nothing is found or an error occurs. A `useEffect` hook then watches for changes to the `storedValue` and updates local storage accordingly, ensuring the state and storage remain synchronized.

Persist React State with a useLocalStorage Hook

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