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name: typescript description: TypeScript/JavaScript coding standards. Use when working on TS/JS code to ensure type safety, proper async handling, and clean code style.

TypeScript / JavaScript

Critical rules for TypeScript and JavaScript development.

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Types & Safety

• Use strict TypeScript (strict: true); avoid any, unknown only when truly unknown
• Prefer interface for object shapes; type for unions/intersections/utilities
• No implicit any; explicit return types on exported functions
• Use as const for literals; avoid type assertions (as) unless unavoidable
• Nullish: prefer ?? over ||; use optional chaining ?. over manual checks

Code Style

• const by default; let only when mutation needed; never var
• Destructure props/objects at function entry
• Arrow functions for callbacks; named functions for top-level/exported
• No dead code, unused imports, or commented-out blocks

Async & Error Handling

• Always await promises or explicitly handle them; no floating promises
• Use try/catch for async; propagate errors with context
• Avoid .then()/.catch() chains; prefer async/await

Modules & Imports

• Imports at file top, grouped: external → internal → types
• Prefer named exports; default exports only for pages/components where framework requires
• No circular imports