>_SkillsHub▋

> typescript-language

Modern TypeScript standards for type safety and maintainability. Use when working with types, interfaces, generics, enums, unions, or tsconfig settings. (triggers: **/*.ts, **/*.tsx, tsconfig.json, type, interface, generic, enum, union, intersection, readonly, const, namespace)

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SKILL.md•typescript-language

TypeScript Language Patterns

Priority: P0 (CRITICAL)

Implementation Guidelines

  • Type Annotations: Explicit params/returns. Infer locals.
  • Interfaces vs Types: interface for APIs. type for unions.
  • Strict Mode: strict: true. Null Safety: ?. and ??.
  • Enums: Literal unions or as const. No runtime enum.
  • Generics: Reusable, type-safe code.
  • Type Guards: typeof, instanceof, predicates.
  • Utility Types: Partial, Pick, Omit, Record.
  • Immutability: readonly arrays/objects. Const Assertions: as const, satisfies.
  • Template Literals: on${Capitalize<string>}.
  • Discriminated Unions: Literal kind property.
  • Advanced: Mapped, Conditional, Indexed types.
  • Access: Default public. Use private/protected or #private.
  • Branded Types: string & { __brand: 'Id' }.

Anti-Patterns

  • No any: NEVER use any. Use unknown or specific interfaces.
  • No Function: Use signature () => void.
  • No enum: Runtime cost.
  • No !: Use narrowing.
  • NO LINT DISABLE: PROHIBITED. Fix issues properly.

Testing

  • Mocking: Use jest.Mocked<T> or as unknown as T.
  • Checklist: Check method existence, match error constants, satisfy required properties.
  • References: See references/TESTING.md for common issues/solutions.

Code

// Branded Type
type UserId = string & { __brand: 'Id' };

// Satisfies (Validate + Infer)
const cfg = { port: 3000 } satisfies Record<string, number>;

// Discriminated Union
type Result<T> = { kind: 'ok'; data: T } | { kind: 'err'; error: Error };

Reference & Examples

For advanced type patterns and utility types: See references/REFERENCE.md.

Related Topics

best-practices | security | tooling

> related_skills --same-repo

> typescript-tooling

Development tools, linting, and build config for TypeScript. Use when configuring ESLint, Prettier, Jest, Vitest, tsconfig, or any TS build tooling. (triggers: tsconfig.json, .eslintrc.*, jest.config.*, package.json, eslint, prettier, jest, vitest, build, compile, lint)

> typescript-security

Secure coding practices for TypeScript. Use when validating input, handling auth tokens, sanitizing data, or managing secrets and sensitive configuration. (triggers: **/*.ts, **/*.tsx, validate, sanitize, xss, injection, auth, password, secret, token)

> typescript-best-practices

Idiomatic TypeScript patterns for clean, maintainable code. Use when writing or refactoring TypeScript classes, functions, modules, or async logic. (triggers: **/*.ts, **/*.tsx, class, function, module, import, export, async, promise)

> swift-tooling

Standards for SPM, Build Configs, and Code Quality. Use when managing Swift packages with SPM, configuring build settings, or enforcing Swift code quality. (triggers: Package.swift, .swiftlint.yml, package, target, dependency)

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first seenMar 17, 2026
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┌ repo

HoangNguyen0403/agent-skills-standard
by HoangNguyen0403
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┌ tags

#typescript
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