localStorage vs sessionStorage?

localStorage persists across tabs/sessions; sessionStorage clears when tab closes.

Store tokens in localStorage?

Avoid for sensitive auth. Prefer httpOnly cookies for XSS resistance.

Roughly 5MB per origin, so do not store large blobs.

Save light/dark and apply on load.

Toggle

Theme: (loading)

Reload page and the theme should persist.

localStorage.setItem('theme', 'dark');
const theme = localStorage.getItem('theme') ?? 'light';

Round-trip objects with parse/stringify.

Save

{}

Stores sample preferences object.

localStorage.setItem('prefs', JSON.stringify({ font: 16 }));
const prefs = JSON.parse(localStorage.getItem('prefs') || '{}');

Delete one key or wipe origin storage.

Clear

Prefer removeItem over clear for one feature.

localStorage.removeItem('token');
// localStorage.clear() wipes all keys

localStorage vs sessionStorage?: localStorage persists across tabs/sessions; sessionStorage clears when tab closes.
Store tokens in localStorage?: Avoid for sensitive auth. Prefer httpOnly cookies for XSS resistance.
Size limit?: Roughly 5MB per origin, so do not store large blobs.