jungho-git/typescript

TypeScript

• Shared examples and formatting reference: references/EXAMPLE.md.
• Keep new guidance, snippets, and edits aligned with that file.

Scope

Use this rule when:

• editing .ts, .tsx, .mts, or .cts files
• changing props, request shapes, returned data, events, or state transitions
• adding or tightening public types
• preserving runtime/module compatibility

TypeScript should make boundary contracts explicit without rewriting stable logic for style.

Type Rules

• Type public functions, props, request objects, response objects, and returned values.
• Prefer concrete types or unknown; do not use any casually.
• Do not silence type errors with as any, // @ts-ignore, or broad assertions.
• Validate data where it enters or leaves the current unit.
• Normalize reused scalar values once near the top of the block.
• Do not claim type safety while external data remains unchecked.

Runtime And Modules

• Run TypeScript with bun unless the user or project requires another runner.
• Use bun, bun -e, bun repl, bunx, or bun x instead of Node/npm fallbacks.
• Preserve explicit import extensions when the repository uses them.
• Do not switch ESM/CommonJS styles unless the runtime boundary requires it.
• Keep exports consistent with local file patterns.
• Do not introduce package-manager, bundler, or tsconfig changes for a local type fix unless required.

Function Shape

• Keep related logic cohesive.
• Extract only for real duplication, unavoidable complexity, typed boundary isolation, or a testable contract.
• Do not rewrite stable JavaScript logic only to satisfy type-style preference.
• Follow JavaScript formatting/comment rules unless TypeScript syntax requires otherwise.

Formatting

• Use Stroustrup clause layout for else, catch, and finally.
• Always use braces for control-flow bodies.
• Prefer early returns.
• Use compact standard style with no vertical alignment.
• Match repository file header fields when a header is used.
• Keep object keys double-quoted when local code uses JSON-like object style.

Validation Focus

• input and output shapes
• caller and consumer assumptions
• async error paths
• type narrowing at external boundaries
• runtime compatibility with Bun
• checks actually run vs not run