Utility Types — Animate | AI Wisdom

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🎞 ANIMATE · Mode 3 of 5 · +100 XP— Utility Types
📋Partial/Required
⚙️Pick/Omit
🔄Record
✅Advanced
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Partial/Required
Partial<T> makes all fields optional — ideal for PATCH payloads💡 Analogy
Like a form where every field has a default value — you only fill in what you want to change.
Partial<User> converts all required fields to optional (adds ?). Used for update operations where you only send changed fields.
Console Output
> const update: Partial<User> = { name: "Bob" }; // OK
> const full: User = { name: "Bob" }; // Error — missing id, email, age
●utility-types.ts
Partial/RequiredL3–7
1interface User { id: string; name: string; email: string; age: number; }
2 
3// Partial — all fields optional (useful for update payloads)
4type UserUpdate = Partial<User>;
5// { id?: string; name?: string; email?: string; age?: number }
6 
7// Required — all fields required (opposite of Partial)
8type UserRequired = Required<Partial<User>>;
9 
10// Pick — select subset of keys
11type UserPreview = Pick<User, 'id' | 'name'>;
12// { id: string; name: string }
13 
14// Omit — exclude subset of keys
15type UserPublic = Omit<User, 'email' | 'age'>;
16// { id: string; name: string }
17 
18// Record — typed key-value map
19type RolePermissions = Record<'admin' | 'user' | 'guest', string[]>;
20const perms: RolePermissions = {
21  admin: ['read', 'write', 'delete'],
22  user:  ['read', 'write'],
23  guest: ['read'],
24};
25 
26// ReturnType and Awaited
27async function fetchUser(id: string): Promise<User> {
28  return JSON.parse('{}');
29}
30type FetchResult = Awaited<ReturnType<typeof fetchUser>>; // User
31 
32// NonNullable — remove null/undefined
33type SafeId = NonNullable<string | null | undefined>; // string
33 lines
Timeline — 4 Steps
Partial/Required
Partial<T> makes all fields optional — ideal for PATCH payloads💡 Analogy
Like a form where every field has a default value — you only fill in what you want to change.
Partial<User> converts all required fields to optional (adds ?). Used for update operations where you only send changed fields.
Console Output
> const update: Partial<User> = { name: "Bob" }; // OK
> const full: User = { name: "Bob" }; // Error — missing id, email, age

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Partial<T> makes all fields optional — ideal for PATCH payloads

💡 Analogy

Like a form where every field has a default value — you only fill in what you want to change.

Partial<User> converts all required fields to optional (adds ?). Used for update operations where you only send changed fields.

Console Output

> const update: Partial<User> = { name: "Bob" }; // OK
> const full: User = { name: "Bob" }; // Error — missing id, email, age

Partial<T> makes all fields optional — ideal for PATCH payloads

💡 Analogy

Like a form where every field has a default value — you only fill in what you want to change.

Partial<User> converts all required fields to optional (adds ?). Used for update operations where you only send changed fields.

Console Output

> const update: Partial<User> = { name: "Bob" }; // OK
> const full: User = { name: "Bob" }; // Error — missing id, email, age