typescript-pro-skill_skill

Overview

This skill provides expert TypeScript guidance focused on advanced type system features, generic programming, and type-safe application architecture. It leverages TypeScript 5+ capabilities to design robust, maintainable code with strong compile-time guarantees. The skill helps teams build developer-friendly APIs, migrate JavaScript codebases, and enforce runtime validation when needed.

How this skill works

I analyse code, API contracts, and design requirements to produce precise TypeScript types, utilities, and migration plans. I create typed API schemas, generic helpers, template literal types, and patterns for gradual migration and strict mode adoption. I can also combine compile-time types with runtime validators (e.g., Zod) and suggest build or compiler optimizations for large projects.

When to use it

• Designing complex type systems with advanced generics, mapped types, and conditional types
• Building fully type-safe API clients and cross-boundary contracts (frontend↔backend)
• Migrating a large JavaScript codebase to TypeScript incrementally
• Troubleshooting difficult type inference or compilation errors
• Creating libraries, SDKs, or framework integrations that require stable type APIs

Best practices

• Define a single source of truth for API contracts and extract types via TypeScript inference
• Prefer explicit return and parameter types on public APIs to avoid fragile inference
• Combine compile-time types with runtime validation (Zod) for untrusted input
• Migrate gradually: enable allowJs/checkJs, add JSDoc, then rename and enable strict mode
• Use template literal and branded types to validate environment variables, routes, and CSS classes

Example use cases

• Generate a type-safe REST client from a contract object that provides autocompletion and compile-time checks
• Create discriminated unions and branded types for a shared domain model across services
• Migrate legacy JS project in phases: allowJs → JSDoc hints → checkJs → .ts renames → strict
• Add Zod runtime schemas to validate API responses while preserving TypeScript types
• Optimize tsconfig and module resolution to reduce build times in a monorepo or large repo