Omit and Record

Learn Omit for removing and Record for mapping.

Omit and Record

Omit<T, K> removes from T the properties listed in K and keeps the rest. Record<K, V> builds an object type that stores a V value for every K key. Together they are handy for narrowing an interface and storing the result in a key-value table.

interface Urun { ad: string; fiyat: number; }
type Adetli = Omit<Urun, "fiyat">;
type Stok = Record<string, number>;

Mapping with Record

Record<K, V> is an object type where each key holds a value of the same type V. For example Record<string, number> maps city names to populations. For a fixed key set you can also use a union of keys like Record<"a" | "b", number>.

Exercise Stock table

Define type Stok as Record<string, number>. Assign the object { elma: 5, armut: 3 } to a variable stoklar (of type Stok). Print stoklar.elma with console.log.

Show example solution

type Stok = Record<string, number>;
const stoklar: Stok = { elma: 5, armut: 3 };
console.log(stoklar.elma);

Test yourself

What does <code>Omit<Urun, "fiyat"></code> produce?
```
interface Urun { ad: string; fiyat: number; }
type T = Omit<Urun, "fiyat">;
```
- A type with all properties optional
- A type with all properties required
- A type with fiyat removed and the rest kept
- A type with only the fiyat property
Show answer

A type with fiyat removed and the rest kept — Omit removes the named properties and keeps the rest. Keeping only one is Pick, making optional is Partial, making required is Required.

Mapping type with Record

type Stok = ____<string, number>;

Show answer

type Stok = Record<string, number>;

Omit and Record parts

Omit<T, K>

Removes properties in K
Omit<Urun, "fiyat">

Type with fiyat removed
Record<K, V>

Key-to-value mapping
Record<string, number>

Each string key maps to a number

Next lesson: Summary - Utility types

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