Typescript Best Practices

TypeScript Best Practices

Guide AI agents in writing high-quality TypeScript code. This skill provides coding standards, architecture patterns, and tools for analysis and scaffolding.

When to Use This Skill

Use this skill when:

• Generating new TypeScript code
• Reviewing TypeScript files for quality issues
• Creating new modules, services, or components
• Refactoring JavaScript to TypeScript
• Answering questions about TypeScript patterns or types
• Designing APIs or interfaces

Do NOT use this skill when:

• Working with pure JavaScript (no TypeScript)
• Debugging runtime errors (use debugging tools)
• Framework-specific patterns (React, Vue, etc. - use framework skills)

Core Principles

1. Type Safety First

Maximize compile-time error detection:

// Prefer unknown over any for unknown types
function processInput(data: unknown): string {
  if (typeof data === "string") return data;
  if (typeof data === "number") return String(data);
  throw new Error("Unsupported type");
}

// Explicit return types for public APIs
export function calculateTotal(items: ReadonlyArray<Item>): number {
  return items.reduce((sum, item) => sum + item.price, 0);
}