Web Storage

Web Storage lets you save data in the browser that survives page reloads.

localStorage

localStorage saves data with no expiration. It stays even after closing the browser:

js
localStorage.setItem("name", "Ada");
localStorage.getItem("name"); // "Ada"
localStorage.removeItem("name");
localStorage.clear();

sessionStorage

sessionStorage works the same but clears when the tab closes:

js
sessionStorage.setItem("key", "value");

localStorage vs sessionStorage

• localStorage: persists forever (until cleared).
• sessionStorage: lasts for the session (tab).

Storing objects

Storage only saves strings, so use JSON:

js
localStorage.setItem("user", JSON.stringify({ name: "Ada" }));
const user = JSON.parse(localStorage.getItem("user"));
user.name; // "Ada"

Common uses

• Remember user preferences and theme.
• Save login tokens.
• Keep shopping cart data.

TL;DR

• localStorage persists data across sessions.
• sessionStorage clears when the tab closes.
• Values must be strings, so use JSON for objects.
• setItem, getItem, removeItem, clear.