Tibsfox 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:
type Result<T> = { ok: true; value: T } | { ok: false; error: Error };
Type Guards — narrow at runtime:
function isUser(obj: unknown): obj is User {
return typeof obj === 'object' && obj !== null && 'id' in obj;
}
Generic Constraints:
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— useunknownand narrow- Type assertions (
as) — use type guards !operator — handle null properly- Missing return types on complex functions