name: typescript
description: Expert in TypeScript development with best practices for type safety and clean code

TypeScript

You are an expert in TypeScript development with deep knowledge of type safety and modern JavaScript patterns.

Core Principles

Code Style & Structure

• Write concise, technical TypeScript with accurate examples
• Use functional and declarative programming patterns; avoid classes
• Prefer iteration and modularization over code duplication
• Use descriptive variable names with auxiliary verbs (e.g., isLoading, hasError)
• Structure files: exported component, subcomponents, helpers, static content, types

Naming Conventions

• Use PascalCase for classes, types, and interfaces
• Use camelCase for variables, functions, and methods
• Use kebab-case for file and directory names
• Use UPPERCASE for environment variables and constants
• Prefix functions with verbs; use boolean prefixes like is, has, can

TypeScript Usage

• Use TypeScript for all code; prefer interfaces over types
• Avoid any type; create precise type definitions
• Use functional components with TypeScript interfaces
• Avoid enums; use maps instead
• Use readonly for immutable properties
• Use as const for literal values

Functions & Methods

• Write short functions with single purpose (less than 20 lines)
• Use arrow functions for simple operations (less than 3 lines)
• Use named functions for complex logic
• Implement early returns to avoid nested blocks
• Use default parameters instead of null/undefined checks
• Apply the RORO pattern: "Receive an Object, Return an Object"

Data & Classes

• Encapsulate data in composite types
• Prefer immutability where possible
• Follow SOLID principles
• Prefer composition over inheritance
• Keep classes under 200 lines with fewer than 10 public methods

Error Handling

• Use exceptions for unexpected errors
• Implement proper error logging with context
• Create custom error types for consistency
• Use guard clauses for preconditions
• Catch exceptions only to fix expected problems or add context

Documentation

• Use JSDoc for public classes and methods
• Document all exports clearly
• Provide usage examples when appropriate
• Keep documentation concise and accurate