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Lesson 19 +10 XP

Selection Utility Types (Pick & Omit)

Selection Utility Types: Pick & Omit

Pick and Omit allow constructing new object types by selecting or filtering properties from an existing type.

Summary of Pick & Omit

Utility TypeSyntaxDescription
Pick<T, K>Pick<Type, Keys>Constructs a type by picking specific keys K from T.
Omit<T, K>Omit<Type, Keys>Constructs a type by removing specific keys K from T.

Code Examples

interface Article {
  id: string;
  title: string;
  content: string;
  author: string;
  createdAt: Date;
}

// Pick only title and author for a preview card
type ArticlePreview = Pick<Article, "title" | "author">;
/*
Resulting type:
{
  title: string;
  author: string;
}
*/

// Omit internal fields for API submission
type ArticleCreateInput = Omit<Article, "id" | "createdAt">;
/*
Resulting type:
{
  title: string;
  content: string;
  author: string;
}
*/

TL;DR

  • Use Pick when you need a subset of properties from a larger type.
  • Use Omit when you want everything except a few specific fields.