Partial

Learn to make all properties optional with Partial.

Partial

Partial<T> makes every property of T optional. It behaves as if each property got a ?; properties you leave out can be undefined. It is ideal for updates or partial data flows where only some fields of an object arrive.

interface Kullanici {
  ad: string;
  yas: number;
}
function guncelle(u: Partial<Kullanici>) {
  // u.ad and u.yas optional
}

The partial update pattern

Partial shines in update functions. When the parameter is Partial<Kullanici>, the caller supplies only the fields they want to change. The body skips missing fields with an undefined check. This keeps calls concise without losing type safety.

Exercise Partial update

Define interface Kullanici with ad: string and yas: number. Write function goster(u: Partial<Kullanici>): void; in the body, if u.ad is present, print it with console.log (otherwise skip). Call goster({ ad: "Deniz" }).

Show example solution

interface Kullanici {
  ad: string;
  yas: number;
}
function goster(u: Partial<Kullanici>): void {
  if (u.ad) {
    console.log(u.ad);
  }
}
goster({ ad: "Deniz" });

Test yourself

What does <code>Partial<Kullanici></code> provide?
```
interface Kullanici { ad: string; yas: number; }
function guncelle(u: Partial<Kullanici>) {}
```
- Makes all properties optional
- Makes all properties required
- Removes some properties
- Makes all properties readonly
Show answer

Makes all properties optional — Partial adds ? to every property, making them all optional. Required makes them required, Omit removes them, Readonly makes them readonly.

Add Partial

interface Ayar { tema: string; ses: boolean; }
function ayarla(a: ____<Ayar>) {
  // a.tema ve a.ses isteğe bağlı
}

Show answer

interface Ayar { tema: string; ses: boolean; }
function ayarla(a: Partial<Ayar>) {
  // a.tema ve a.ses isteğe bağlı
}

Partial parts

Partial<T>

Makes all properties optional
Partial<Kullanici>

Use on a type
u.ad?

Result: optional property
guncelle({ yas: 30 })

Call with partial data

Next lesson: Required and Pick

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