# Typescript

> >

- **Type:** Skill
- **Install:** `agentstack add skill-gentleman-programming-gentleman-skills-typescript`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Gentleman-Programming](https://agentstack.voostack.com/s/gentleman-programming)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [Gentleman-Programming](https://github.com/Gentleman-Programming)
- **Source:** https://github.com/Gentleman-Programming/Gentleman-Skills/tree/main/curated/typescript

## Install

```sh
agentstack add skill-gentleman-programming-gentleman-skills-typescript
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

## Const Types Pattern (REQUIRED)

```typescript
// ✅ 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.

## Flat Interfaces (REQUIRED)

```typescript
// ✅ 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
}

interface Admin extends User {
  permissions: string[];
}

// ❌ NEVER: Inline nested objects
interface User {
  address: { street: string; city: string };  // NO!
}
```

## Never Use `any`

```typescript
// ✅ Use unknown for truly unknown types
function parse(input: unknown): User {
  if (isUser(input)) return input;
  throw new Error("Invalid input");
}

// ✅ Use generics for flexible types
function first(arr: T[]): T | undefined {
  return arr[0];
}

// ❌ NEVER
function parse(input: any): any { }
```

## Utility Types

```typescript
Pick     // Select fields
Omit              // Exclude fields
Partial                 // All optional
Required                // All required
Readonly                // All readonly
Record          // Object type
Extract     // Extract from union
Exclude           // Exclude from union
NonNullable         // Remove null/undefined
ReturnType         // Function return type
Parameters         // Function params tuple
```

## Type Guards

```typescript
function isUser(value: unknown): value is User {
  return (
    typeof value === "object" &&
    value !== null &&
    "id" in value &&
    "name" in value
  );
}
```

## Import Types

```typescript
import type { User } from "./types";
import { createUser, type Config } from "./utils";
```

## Keywords
typescript, ts, types, interfaces, generics, strict mode, utility types

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Gentleman-Programming](https://github.com/Gentleman-Programming)
- **Source:** [Gentleman-Programming/Gentleman-Skills](https://github.com/Gentleman-Programming/Gentleman-Skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-gentleman-programming-gentleman-skills-typescript
- Seller: https://agentstack.voostack.com/s/gentleman-programming
- Browse the marketplace: https://agentstack.voostack.com/browse

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