Typescript

Enforces strict TypeScript patterns with a focus on const object mappings over raw union types, flat interfaces, and discriminated unions for coupled optional props. Auto-triggers when you're writing types or interfaces. The const-first pattern is opinionated but solid: you define a const object then extract the type, giving you runtime values and a single source of truth. The coupled optionals section is the most interesting bit, using discriminated unions with never to prevent half-states like having onPageChange without currentPage. Includes type guards, utility type quick reference, and a hard ban on any. Good for teams that want consistency without having to debate these choices in every PR.

skills.sh installs: 254
GitHub stars: 15.2K
last updated: Aug 21, 2026

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Install

$ npx -y skills add prowler-cloud/prowler --skill typescript --agent claude-code

Installs into .claude/skills of the current project.

Files

Const Types Pattern (REQUIRED)

// ✅ ALWAYS: Create const object first, then extract type
const STATUS = {
  ACTIVE: "active",
  INACTIVE: "inactive",
  PENDING: "pending",
} as const;

type Status = (typeof STATUS)[keyof typeof STATUS];

// ❌ NEVER: Direct union types
type Status = "active" | "inactive" | "pending";

Why? Single source of truth, runtime values, autocomplete, easier refactoring.

When you need the ordered list too (iteration, z.enum), a const array works the same way:

// ui/types/severities.ts
export const SEVERITY_LEVELS = ["critical", "high", "medium", "low", "informational"] as const;
export type SeverityLevel = (typeof SEVERITY_LEVELS)[number];

// Known key set -> Record<Union, ...> (typos fail to compile)
export const SEVERITY_DISPLAY_NAMES: Record<SeverityLevel, string> = { /* ... */ };

Flat Interfaces (REQUIRED)

// ✅ ALWAYS: One level depth, nested objects → dedicated interface
interface UserAddress {
  street: string;
  city: string;
}

interface User {
  id: string;
  name: string;
  address: UserAddress;  // Reference, not inline
}

SKILL.md on GitHub