Bits of .NET

💾 Local Storage = Browser Database

Need to store user data in browser? Local storage persists data across sessions. No server needed.

📝 Local Storage Methods

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

// Get data
const value = localStorage.getItem('key');

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

// Clear all data
localStorage.clear();

// Get all keys
const keys = Object.keys(localStorage);

// Check if key exists
if (localStorage.getItem('key') !== null) {
    // Key exists
}

// Store objects (JSON)
const user = { name: 'Alice', age: 30 };
localStorage.setItem('user', JSON.stringify(user));
const userData = JSON.parse(localStorage.getItem('user'));

🎯 Practical Examples

// User preferences
function saveTheme(theme) {
    localStorage.setItem('theme', theme);
}
function getTheme() {
    return localStorage.getItem('theme') || 'light';
}

// Remember form data
function saveFormData(formData) {
    localStorage.setItem('formData', JSON.stringify(formData));
}
function getFormData() {
    const data = localStorage.getItem('formData');
    return data ? JSON.parse(data) : {};
}

// Shopping cart
const cart = [
    { id: 1, name: 'Product 1', price: 99 },
    { id: 2, name: 'Product 2', price: 149 }
];
localStorage.setItem('cart', JSON.stringify(cart));
const savedCart = JSON.parse(localStorage.getItem('cart') || '[]');

// User session
function saveSession(user) {
    localStorage.setItem('session', JSON.stringify(user));
}
function getSession() {
    const session = localStorage.getItem('session');
    return session ? JSON.parse(session) : null;
}
function clearSession() {
    localStorage.removeItem('session');
}

💡 Limitations

• 5-10 MB storage limit
• String data only (use JSON for objects)
• Not secure (data is plain text)
• Same-origin policy
• Not for sensitive data