What it Does

Makes all properties of a type optional.

Syntax

type PartialType = Partial<OriginalType>;

Use Cases

• Partial updates: When updating an object, not all fields need to be provided.
• Form handling: When form fields can be filled incrementally.
• Configuration objects: Default configs where users can override only specific values.

Detailed Example

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

*// Update function accepting partial user data*
function updateUser(id: number, updates: Partial<User>) {
  *// Only fields provided in 'updates' will be changed*
  return { ...existingUser, ...updates };
}

*// Valid calls - any combination works*
updateUser(1, { name: "Alice" });
updateUser(1, { email: "alice@example.com", age: 25 });
updateUser(1, {}); *// Even empty object is valid*

Key Points

• All properties become optional (?).
• Original type remains unchanged.
• Perfect for update operations where only changed fields are sent.