TypeScript: Pick vs Omit
Pick and Omit are two sides of the same coin. They are both utility types used to derive a new object type by filtering the keys of an existing type.
1. Pick<Type, Keys> (The Whitelist)
Pick constructs a type by selecting a specific set of properties (Keys) from Type.
- Mental Model: "I only want these specific fields."
- Behavior: If you add a new field to the original type, the
Picked type will not have it unless you explicitly add it to the keys.
Example
interface User {
id: number;
name: string;
email: string;
passwordHash: string;
createdAt: Date;
}
// We want a type for displaying a user profile card
type UserProfile = Pick<User, "name" | "email">;
const profile: UserProfile = {
name: "Alice",
email: "alice@example.com"
// id, passwordHash, createdAt are NOT allowed
};2. Omit<Type, Keys> (The Blacklist)
Omit constructs a type by picking all properties from Type and then removing Keys.
- Mental Model: "I want everything except these specific fields."
- Behavior: If you add a new field to the original type, the
Omitted type will automatically include it.
Example
interface User {
id: number;
name: string;
email: string;
passwordHash: string;
createdAt: Date;
}
// We want a type for the user object, but without sensitive data
type SafeUser = Omit<User, "passwordHash">;
const user: SafeUser = {
id: 1,
name: "Alice",
email: "alice@example.com",
createdAt: new Date()
// passwordHash is NOT allowed
};3. Which one to use?
The choice depends on how you want your derived type to react when the base type evolves.
| Feature | Pick |
Omit |
|---|---|---|
| Approach | Whitelist (Inclusive) | Blacklist (Exclusive) |
| Stability | Rigid: New props on base type are ignored. | Flexible: New props on base type are included. |
| Best For | Specific sub-views, DTOs, strict contracts. | Removing metadata, sensitive fields, or internal props. |
Scenario: Adding a field
If we add avatarUrl: string to User:
UserProfile(Pick) will not haveavatarUrl.SafeUser(Omit) will haveavatarUrl.
programming/javascript/typescript/typescript programming/javascript/typescript/utility-types