Mastering TypeScript Utility Types: Partial, Required, Readonly, Record, Pick, Omit & Exclude

TypeScript includes powerful built-in Utility Types that facilitate global type transformations. Mastering these types enables engineers to write DRY, robust type definitions.

Core Built-in Utility Types

• •Partial: Makes all properties optional.
• •Required: Makes all properties required.
• •Readonly: Makes all properties immutable.
• •Record: Constructs an object type with key type K and value type T.
• •Pick: Constructs a type by picking specific properties K from T.
• •Omit: Constructs a type by removing properties K from T.

interface UserProfile {
  id: string;
  username: string;
  email: string;
  bio?: string;

// Pick only public fields type PublicUser = Pick;

// Omit sensitive email field type SafeUser = Omit;

// Make profile fields optional for update operations type UpdateUserProfileInput = Partial>; ```

Custom Mapped Types (Interview Question)

Implement custom MyOmit without using the built-in Omit:

type MyOmit<T, K extends keyof T> = {
  [P in keyof T as P extends K ? never : P]: T[P];
};

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Practice TypeScript Coding Live Test TypeScript generic utilities live in a shared editor. [Create a Free Pairlet Room](https://www.pairlet.dev/interview/new).