typescript

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description: TypeScript coding standards and best practices for modern web development globs: **/.ts, **/.tsx, **/*.d.ts

TypeScript Best Practices

Type System

• Prefer interfaces over types for object definitions
• Use type for unions, intersections, and mapped types
• Avoid using any, prefer unknown for unknown types
• Use strict TypeScript configuration
• Leverage TypeScript's built-in utility types
• Use generics for reusable type patterns

Naming Conventions

• Use PascalCase for type names and interfaces
• Use camelCase for variables and functions
• Use UPPER_CASE for constants
• Use descriptive names with auxiliary verbs (e.g., isLoading, hasError)
• Prefix interfaces for React props with 'Props' (e.g., ButtonProps)

Code Organization

• Keep type definitions close to where they're used
• Export types and interfaces from dedicated type files when shared
• Use barrel exports (index.ts) for organizing exports
• Place shared types in a types directory
• Co-locate component props with their components

Functions

• Use explicit return types for public functions
• Use arrow functions for callbacks and methods
• Implement proper error handling with custom error types
• Use function overloads for complex type scenarios
• Prefer async/await over Promises

Best Practices

• Enable strict mode in tsconfig.json
• Use readonly for immutable properties
• Leverage discriminated unions for type safety
• Use type guards for runtime type checking
• Implement proper null checking
• Avoid type assertions unless necessary

Error Handling

• Create custom error types for domain-specific errors
• Use Result types for operations that can fail
• Implement proper error boundaries
• Use try-catch blocks with typed catch clauses
• Handle Promise rejections properly

Patterns

• Use the Builder pattern for complex object creation
• Implement the Repository pattern for data access
• Use the Factory pattern for object creation
• Leverage dependency injection
• Use the Module pattern for encapsulation