typescript-docs

SKILL.md

TypeScript Documentation

Generate production-ready TypeScript documentation with layered architecture for multiple audiences. Supports API docs with TypeDoc, ADRs, and framework-specific patterns.

Overview

Use JSDoc annotations for inline documentation, TypeDoc for API reference generation, and ADRs for tracking design choices.

Key capabilities:

TypeDoc configuration and API documentation generation

JSDoc patterns for all TypeScript constructs

ADR creation and maintenance

Framework-specific patterns (NestJS, React, Express, Angular, Vue)

ESLint validation rules for documentation quality

GitHub Actions pipeline setup

When to Use

Use this skill when creating API documentation, architectural decision records, code examples, or framework-specific patterns for NestJS, Express, React, Angular, or Vue.
Quick Reference

Tool
Purpose
Command

TypeDoc
API documentation generation
npx typedoc

Compodoc
Angular documentation
npx compodoc -p tsconfig.json

ESLint JSDoc
Documentation validation
eslint --ext .ts src/

JSDoc Tags

Tag
Use Case

@param
Document parameters

@returns
Document return values

@throws
Document error conditions

@example
Provide code examples

@remarks
Add implementation notes

@see
Cross-reference related items

@deprecated
Mark deprecated APIs

Instructions

1. Configure TypeDoc

npm install --save-dev typedoc typedoc-plugin-markdown

{
  "entryPoints": ["src/index.ts"],
  "out": "docs/api",
  "theme": "markdown",
  "excludePrivate": true,
  "readme": "README.md"
}

2. Add JSDoc Comments

/**
 * Service for managing user authentication
 *
 * @remarks
 * Handles JWT-based authentication with bcrypt password hashing.
 *
 * @example
 * ```typescript
 * const authService = new AuthService(config);
 * const token = await authService.login(email, password);
 * ```
 *
 * @security
 * - Passwords hashed with bcrypt (cost factor 12)
 * - JWT tokens signed with RS256
 */
@Injectable()
export class AuthService {
  /**
   * Authenticates a user and returns access tokens
   * @param credentials - User login credentials
   * @returns Authentication result with tokens
   * @throws {InvalidCredentialsError} If credentials are invalid
   */
  async login(credentials: LoginCredentials): Promise<AuthResult> {
    // Implementation
  }
}

3. Create an ADR

# ADR-001: TypeScript Strict Mode Configuration

## Status
Accepted

## Context
What is the issue motivating this decision?

## Decision
What change are we proposing?

## Consequences
What becomes easier or more difficult?

4. Set Up CI/CD Pipeline

name: Documentation
on:
  push:
    branches: [main]
    paths: ['src/**', 'docs/**']

jobs:
  generate-docs:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npm run docs:generate
      - run: npm run docs:validate

5. Validate Documentation

{
  "rules": {
    "jsdoc/require-description": "error",
    "jsdoc/require-param-description": "error",
    "jsdoc/require-returns-description": "error",
    "jsdoc/require-example": "warn"
  }
}

If validation fails: review ESLint errors, fix JSDoc comments (add missing descriptions, add @param/@returns/@throws where absent), re-run eslint --ext .ts src/ until all errors pass before committing.

Examples

Documenting a React Hook

/**
 * Custom hook for fetching paginated data
 *
 * @remarks
 * This hook manages loading states, error handling, and automatic
 * refetching when the page or filter changes.
 *
 * @example
 * ```tsx
 * function UserList() {
 *   const { data, isLoading, error } = usePaginatedData('/api/users', {
 *     page: currentPage,
 *     limit: 10
 *   });
 *
 *   if (isLoading) return <Spinner />;
 *   if (error) return <ErrorMessage error={error} />;
 *   return <UserTable users={data.items} />;
 * }
 * ```
 *
 * @param endpoint - API endpoint to fetch from
 * @param options - Pagination and filter options
 * @returns Paginated response with items and metadata
 */
export function usePaginatedData<T>(
  endpoint: string,
  options: PaginationOptions
): UsePaginatedDataResult<T> {
  // Implementation
}

Documenting a Utility Function

/**
 * Validates email addresses using RFC 5322 specification
 *
 * @param email - Email address to validate
 * @returns True if email format is valid
 *
 * @example
 * ```typescript
 * isValidEmail('user@example.com'); // true
 * isValidEmail('invalid-email');      // false
 * ```
 *
 * @performance
 * O(n) where n is the email string length
 *
 * @see {@link https://tools.ietf.org/html/rfc5322} RFC 5322 Specification
 */
export function isValidEmail(email: string): boolean {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return emailRegex.test(email);
}

NestJS Controller Documentation

/**
 * REST API endpoints for user management
 *
 * @remarks
 * All endpoints require authentication via Bearer token.
 * Rate limiting: 100 requests per minute per user.
 *
 * @example
 * ```bash
 * curl -H "Authorization: Bearer <token>" https://api.example.com/users/123
 * ```
 *
 * @security
 * - All endpoints use HTTPS
 * - JWT tokens expire after 1 hour
 * - Sensitive data is redacted from logs
 */
@Controller('users')
export class UsersController {
  /**
   * Retrieves a user by ID
   * @param id - User UUID
   * @returns User profile (password excluded)
   */
  @Get(':id')
  async getUser(@Param('id') id: string): Promise<UserProfile> {
    // Implementation
  }
}

Best Practices

Document Public APIs: All public methods, classes, and interfaces

Use @example: Provide runnable examples for complex functions

Include @throws: Document all possible errors

Add @see: Cross-reference related functions/types

Use @remarks: Add implementation details and notes

Document Generics: Explain generic constraints and usage

Include Performance Notes: Document time/space complexity

Add Security Warnings: Highlight security considerations

Keep Updated: Update docs when code changes

Don't document obvious code: Focus on why, not what

Constraints and Warnings

Private Members: Use @private or exclude from TypeDoc output

Complex Types: Document generic constraints and type parameters

Breaking Changes: Use @deprecated with migration guidance

Security Info: Never include secrets or credentials in documentation

Link Validity: Ensure @see references point to valid locations

Example Code: All examples should be runnable and tested

Versioning: Keep documentation in sync with code versions

References

references/jsdoc-patterns.md — JSDoc patterns for interfaces, functions, classes, generics, and unions

references/framework-patterns.md — Framework-specific patterns for NestJS, React, Express, and Angular

references/adr-patterns.md — ADR templates and examples

references/pipeline-setup.md — CI/CD pipeline configuration for documentation

references/validation.md — ESLint rules and validation checklists

references/typedoc-configuration.md — Complete TypeDoc configuration options

references/examples.md — Additional code examples