typescript-patterns
TypeScript best practices and patterns. Use when writing TypeScript, fixing type errors, or working with generics.
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- Tibsfox/gsd-skill-creator
- Last source activity
- April 25, 2026 at 21:14
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- typescript-patterns
- description
- TypeScript best practices and patterns. Use when writing TypeScript, fixing type errors, or working with generics.
- version
- 1.0.0
- format
- 2025-10-02T00:00:00.000Z
- triggers
- ["writing TypeScript, fixing type errors, or working with generics"]
- updated
- 2026-04-25T00:00:00.000Z
- status
- ACTIVE
# TypeScript Patterns
## Type vs Interface
| Use Case | Prefer |
|----------|--------|
| Object shape | interface |
| Union types | type |
| Extending shapes | interface |
| Intersection | type |
| Tuple/primitives | type |
## Key Patterns
**Discriminated Unions** — model state with tagged types:
```typescript
type Result<T> = { ok: true; value: T } | { ok: false; error: Error };
```
**Type Guards** — narrow at runtime:
```typescript
function isUser(obj: unknown): obj is User {
return typeof obj === 'object' && obj !== null && 'id' in obj;
}
```
**Generic Constraints:**
```typescript
function getProperty<T, K extends keyof T>(obj: T, key: K): T[K] { return obj[key]; }
```
## Utility Types
| Type | Purpose |
|------|---------|
| Partial\<T\> | All optional |
| Required\<T\> | All required |
| Pick\<T,K\> | Select properties |
| Omit\<T,K\> | Remove properties |
| Record\<K,V\> | Key-value map |
| ReturnType\<T\> | Function return type |
## Avoid
- `any` — use `unknown` and narrow
- Type assertions (`as`) — use type guards
- `!` operator — handle null properly
- Missing return types on complex functions
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