Snippet

Generic Custom Hook for LocalStorage

This generic hook synchronizes state with LocalStorage while handling the Next.js SSR environment check (checking if window is defined).

snippet.js

javascript

function useLocalStorage<T>(key: string, initialValue: T) {
  const [storedValue, setStoredValue] = useState<T>(() => {
    if (typeof window === 'undefined') return initialValue;
    const item = window.localStorage.getItem(key);
    return item ? JSON.parse(item) : initialValue;
  });
 
  const setValue = (value: T | ((val: T) => T)) => {
    const valueToStore = value instanceof Function ? value(storedValue) : value;
    setStoredValue(valueToStore);
    window.localStorage.setItem(key, JSON.stringify(valueToStore));
  };
 
  return [storedValue, setValue] as const;
}

nextjs

Breakdown

useLocalStorage<T>

Uses TypeScript generics to allow any data type to be stored safely.

if (typeof window === 'undefined')

Ensures the code doesn't crash during Server-Side Rendering (SSR).

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Generic Custom Hook for LocalStorage

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