5 TypeScript Utility Types You Should Know

TypeScript has built-in utility types that transform existing types. Here are the essential ones.

1. Partial

Makes all properties optional:

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interface User {
  id: number;
  name: string;
  email: string;
}

// All properties optional
type UpdateUser = Partial<User>;

function updateUser(id: number, updates: Partial<User>) {
  // Can pass any subset of User properties
}

updateUser(1, { name: "John" }); // ✅
updateUser(1, { email: "new@email.com" }); // ✅

2. Required

Makes all properties required (opposite of Partial):

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interface Config {
  host?: string;
  port?: number;
  ssl?: boolean;
}

// All properties now required
type StrictConfig = Required<Config>;

const config: StrictConfig = {
  host: "localhost",
  port: 3000,
  ssl: true,
  // Missing any = error!
};

3. Pick

Select specific properties:

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interface User {
  id: number;
  name: string;
  email: string;
  password: string;
  createdAt: Date;
}

// Only id and name
type UserPreview = Pick<User, "id" | "name">;

// { id: number; name: string; }

4. Omit

Remove specific properties:

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interface User {
  id: number;
  name: string;
  email: string;
  password: string;
}

// Everything except password
type SafeUser = Omit<User, "password">;

// { id: number; name: string; email: string; }

5. Record

Create object type with specific keys and value type:

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type Status = "pending" | "active" | "done";

// Object with Status keys, number values
const taskCount: Record<Status, number> = {
  pending: 5,
  active: 3,
  done: 12,
};

// Dynamic key mapping
type UserRoles = Record<string, string[]>;
const roles: UserRoles = {
  admin: ["read", "write", "delete"],
  user: ["read"],
};

Bonus: Combining Them

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interface User {
  id: number;
  name: string;
  email: string;
  password: string;
  role: "admin" | "user";
}

// Updatable fields (no id, partial)
type UserUpdate = Partial<Omit<User, "id">>;

// Public user data
type PublicUser = Omit<User, "password" | "email">;

// Form data with required name
type UserForm = Partial<User> & Required<Pick<User, "name">>;

Cheat Sheet

Type	What it does
`Partial`	All optional
`Required`	All required
`Pick`	Only these keys
`Omit`	Everything except
`Record`	Object with K keys

Learn these five and you'll cover 90% of type transformation needs.

5 TypeScript Utility Types You Should Know

1. Partial

2. Required

3. Pick

4. Omit

5. Record

Bonus: Combining Them

Cheat Sheet

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