Adopt modern JavaScript syntax and patterns to improve code quality and maintainability. This includes using current language features over deprecated alternatives, proper variable declarations, and modern conditional operators.

Key practices to follow:

Example of improved JSX conditional rendering:

// Instead of:
{actionData && actionData.error && (
  <div>Error occurred</div>
)}

// Use:
{actionData?.error ? (
  <div>Error occurred</div>
) : null}

This approach reduces potential runtime errors, improves readability, and follows current JavaScript and React best practices.