Reading and Writing localStorage in React

localStorage is a built-in browser store with four core methods: setItem(key, value), getItem(key), removeItem(key), and clear(). Data persists across page reloads and browser restarts.

It lives on the window object and is scoped per origin, meaning each domain has its own isolated storage.

Every localStorage call runs synchronously on the main thread. Reading or writing large amounts of data can block rendering and make the UI feel janky.

Because of this, keep stored values small and avoid writing on every keystroke or scroll event.