Implement a generic PartialByKeys<T, K> which takes two type argument T and K.
K specify the set of properties of T that should set to be optional. When K is not provided, it should make all properties optional just like the normal Partial<T>.
For example
interface User {
name: string
age: number
address: string
}
type UserPartialName = PartialByKeys<User, 'name'> // { name?:string; age:number; address:string }
import type { Equal, Expect } from '@type-challenges/utils'
interface User {
name: string
age: number
address: string
}
interface UserPartialName {
name?: string
age: number
address: string
}
interface UserPartialNameAndAge {
name?: string
age?: number
address: string
}
type cases = [
Expect<Equal<PartialByKeys<User, 'name'>, UserPartialName>>,
Expect<Equal<PartialByKeys<User, 'name' | 'age'>, UserPartialNameAndAge>>,
Expect<Equal<PartialByKeys<User>, Partial<User>>>,
// @ts-expect-error
Expect<Equal<PartialByKeys<User, 'name' | 'unknown'>, UserPartialName>>,
]