Secure Input Validation

How to do that?

Well,

1. Never trust user inout, validate and sanitize all data.
2. Use whitelisting over blacklisting for safer input filtering.
3. Implement server-side validation to prevent client-side bypasses.

Example:

function validateInput(input) {
  if (typeof input !== 'string' || input.length > 255) {
    throw new Error('Invalid input');
  }
  return input.replace(/[<>'"]/g, ''); // Basic sanitization
}

Want to learn more? Check out the OWASP Input Validation Cheat Sheet