# Typescript Patterns

> TypeScript type system patterns, generics, utility types, and strict mode best practices. Use when writing or reviewing TypeScript code.

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

## Install

```sh
agentstack add skill-sabahattink-antigravity-fullstack-hq-typescript-patterns
```

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

## About

# TypeScript Patterns

## Core Rules

- Strict mode always (`"strict": true`)
- No `any` — use `unknown` for dynamic values
- Explicit return types on all functions
- `const` over `let`, never `var`

## Type Definitions

### Interfaces vs Types

```typescript
// ✅ Interface for objects/classes (extensible)
interface User {
  id: string
  email: string
  name: string
}

// ✅ Type for unions, primitives, computed
type Status = 'active' | 'inactive' | 'pending'
type UserOrAdmin = User | Admin
type ReadonlyUser = Readonly
```

### Generics

```typescript
// ✅ Reusable generic types
type ApiResponse = {
  data: T
  error: string | null
  status: number
}

type PaginatedResponse = {
  items: T[]
  total: number
  page: number
  limit: number
}

// ✅ Generic functions
const findById = (items: T[], id: string): T | undefined =>
  items.find(item => item.id === id)
```

## Utility Types

```typescript
// Pick specific fields
type UserPreview = Pick

// Omit sensitive fields
type PublicUser = Omit

// Make all optional (for partial updates)
type UpdateUserDto = Partial

// Make all required
type RequiredUser = Required

// Make all readonly
type FrozenUser = Readonly

// Extract from union
type ActiveStatus = Extract

// Record type
type UserMap = Record
```

## Discriminated Unions

```typescript
// ✅ Type-safe error handling
type Result =
  | { success: true; data: T }
  | { success: false; error: string }

const processUser = (id: string): Result => {
  try {
    return { success: true, data: fetchUser(id) }
  } catch (e) {
    return { success: false, error: 'User not found' }
  }
}

// Usage — TypeScript knows the type
const result = processUser('123')
if (result.success) {
  console.log(result.data.name) // User
} else {
  console.log(result.error) // string
}
```

## Type Guards

```typescript
// ✅ Custom type guards
const isUser = (value: unknown): value is User =>
  typeof value === 'object' &&
  value !== null &&
  'id' in value &&
  'email' in value

// ✅ Assertion functions
const assertDefined = (value: T | null | undefined): T => {
  if (value == null) throw new Error('Value is null or undefined')
  return value
}
```

## Async Patterns

```typescript
// ✅ Always type async return values
const fetchUser = async (id: string): Promise => {
  const res = await fetch(`/api/users/${id}`)
  if (!res.ok) throw new Error('Failed to fetch user')
  return res.json() as Promise
}

// ✅ Error handling with unknown
try {
  await fetchUser(id)
} catch (error) {
  if (error instanceof Error) {
    console.error(error.message)
  }
}
```

## Forbidden Patterns

```typescript
// ❌ Never
const data: any = fetchData()
function process(x) { return x }  // implicit any
const obj = {} as User             // unsafe assertion
// @ts-ignore                      // suppressing errors
```

## Source & license

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

- **Author:** [sabahattink](https://github.com/sabahattink)
- **Source:** [sabahattink/antigravity-fullstack-hq](https://github.com/sabahattink/antigravity-fullstack-hq)
- **License:** MIT
- **Homepage:** https://github.com/sabahattink/antigravity-fullstack-hq

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-sabahattink-antigravity-fullstack-hq-typescript-patterns
- Seller: https://agentstack.voostack.com/s/sabahattink
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.