Browser Storage

Web storage keeps string data in the browser. localStorage survives restarts; sessionStorage lasts for the current tab session. Neither is a database or a secure secret store.

Save versioned state

01const key = "arcbyte:progress:v1";
02const state = { version: 1, lesson: "dom", percent: 64 };
03
04try {
05  localStorage.setItem(key, JSON.stringify(state));
06  const saved = JSON.parse(localStorage.getItem(key) ?? "null");
07  if (saved?.version === 1) console.log(saved.lesson);
08} catch (error) {
09  console.warn("Progress could not be stored", error);
10}

Storage can be blocked, full, cleared, or corrupted. Keep the application functional without it and validate parsed shapes.

Choose the right storage

Use cookies when a small value must accompany HTTP requests, IndexedDB for larger structured offline data, and a trusted server when data must sync across devices.

Keep this

Store only small nonsecret device-local state, version the schema, handle failure, and provide a way to clear it.