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Type Aliases
6 exercises
Type aliases give a name to any type so you can reuse it throughout your code:
type UserId = string | number;
type Status = 'idle' | 'loading' | 'success' | 'error';
type Point = { x: number; y: number };This improves readability, reduces duplication, and keeps APIs consistent.
You can create aliases for:
- Unions –
string | numberor'red' | 'green' | 'blue' - Object shapes –
{ id: number; name: string } - Tuples –
[number, number]for fixed-length arrays - Function signatures –
(x: number) => number
In this category, you'll:
- Create type aliases for common patterns in your code
- Use literal unions for small state sets (status, direction, etc.)
- Apply aliases across multiple functions to reduce duplication
- Work with optional and readonly properties in aliases
Keep implementations simple, avoid mutation unless required, and use narrowing to work safely with unions.