typescript

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Description: TypeScript Development Standards Globs: **/.ts, **/.tsx, **/.mts, **/.cts

TypeScript Development Standards

@base.mdc

Core TypeScript Principles

• Leverage TypeScript's static typing to catch errors at compile time
• Avoid using any type unless absolutely necessary
• Use type inference where it improves readability
• Define explicit return types for functions
• Create reusable type definitions for common patterns
• Take advantage of TypeScript's advanced type features when appropriate

Type Definitions

Naming

• Use PascalCase for interface and type names (e.g., UserProfile)
• Prefix interfaces for React component props with component name (e.g., ButtonProps)
• Use descriptive names that convey purpose (e.g., ApiResponse rather than just Response)
• Avoid prefixing interfaces with 'I' (prefer User over IUser)

Structure

• Use interfaces for object shapes primarily
• Use type aliases for unions, intersections, or complex types
• Prefer interfaces for public APIs to support declaration merging
• Keep type definitions close to where they are used
• Export types that are used across multiple files

Type Safety

• Enable strict type checking in tsconfig.json
• Use unknown instead of any when type is unclear
• Use union types to represent values that could be of different types
• Utilize generics for flexible, reusable code
• Add appropriate type guards when narrowing types
• Use readonly modifiers for immutable properties
• Use as const for literal values when appropriate

Best Practices

Modern TypeScript Features

• Use optional chaining (?.) to safely access nested properties
• Use nullish coalescing (??) to provide default values
• Use template literal types for string manipulations
• Apply mapped types to transform existing types
• Use conditional types for type-level programming
• Leverage utility types (e.g., Partial<T>, Required<T>, Pick<T>, Omit<T>)
• Use const assertions for readonly arrays and tuples