Prefer TypeScript for New Files

Prefer TypeScript file extensions for new code

Source: .agents/rules/prefer-typescript-files.mdc

Metadata

• alwaysApply: true

Content

Prefer TypeScript for New Files

• For all new files, use TypeScript extensions:
  • Use .tsx for React files that contain JSX.
  • Use .ts for non-JSX modules, utilities, hooks, services, and types.
• Do not create new .js or .jsx files unless the user explicitly requests it.
• If editing an existing .js/.jsx file, keep the existing extension unless a migration is requested.

// ✅ Preferred
// Button.tsx
export default function Button() {
  return <button>Click</button>;
}

// ✅ Preferred
// formatDate.ts
export const formatDate = (date: Date) => date.toISOString();

// ❌ Avoid for new files
// Button.jsx
// formatDate.js