bew/dotfiles/coder-ts

Goal

Write TypeScript modules with type-only imports, type aliases, and consistent file headers, building on generic conventions.

REQUIRES: load coder-generic skill first.

All TypeScript here is module code: .ts/.tsx files imported by other code, not run directly. Standalone TS scripts are out of scope — this skill ships no script variant.

If working on module code: read <./module-rules.md>.

Rules

• Prefer type aliases for object shapes and unions; reserve interface for declaration merging.
• Mark immutable collections readonly (readonly T[], ReadonlyMap).
• Use as const for literal constants and fixed ordered lists.
• Use === and !==; never == or !=.
• Prefer optional chaining and nullish coalescing over ! non-null assertions.
• Use unknown at untrusted boundaries, then narrow before use — never any.
• When filtering a union-typed collection, use a type guard so narrowing survives downstream.

Comments

• Open every file with a // header: one line stating purpose, then optional paragraphs

separated by blank // lines.

• Document each declaration with a // comment on the line above it.
• See coder-generic for comment content rules.

Testing

TypeScript tests run on Bun's test runner. Import test and expect from "bun:test"; drive time with jest.useFakeTimers() and jest.advanceTimersByTime(...). Run tests with bun test <path>. No dedicated TypeScript testing skill exists yet — ask the user before adding a test framework.