What is the difference between localStorage and sessionStorage?

// Set item
localStorage.setItem('key', 'value');
sessionStorage.setItem('key', 'value');

// Get item
localStorage.getItem('key'); // 'value'

// Remove item
localStorage.removeItem('key');

// Clear all
localStorage.clear();

// Get key by index
localStorage.key(0);

// Length
localStorage.length;

// Storage only accepts strings
const user = { name: 'John', age: 30 };

// Store object
localStorage.setItem('user', JSON.stringify(user));

// Retrieve object
const stored = JSON.parse(localStorage.getItem('user'));

// localStorage: User preferences
localStorage.setItem('theme', 'dark');

// sessionStorage: Form draft
sessionStorage.setItem('formDraft', JSON.stringify(formData));

// Check if exists
if (localStorage.getItem('token')) {
  // User is logged in
}

// Listen for changes from other tabs
window.addEventListener('storage', (e) => {
  console.log(`${e.key} changed from ${e.oldValue} to ${e.newValue}`);
});