Why Security Matters

Security vulnerabilities can expose user data and damage trust. Understanding common attacks helps you prevent them.

Cross-Site Scripting (XSS)

// Vulnerable:
element.innerHTML = userInput; // Never do this!

// Safe:
element.textContent = userInput;
// Or use proper sanitization libraries

SQL Injection

// Vulnerable:
query = "SELECT * FROM users WHERE id = " + userId;

// Safe - parameterized query:
query = "SELECT * FROM users WHERE id = ?";
db.execute(query, [userId]);

CSRF Protection

Best Practices

Use HTTPS everywhere. Validate all input. Implement proper authentication. Keep dependencies updated. Use security headers.

Conclusion

Security should be considered from day one, not added later. Learn OWASP Top 10 for comprehensive coverage.