題目
中文
給定一個只包含字符串類型的元組類型T和一個類型 U, 遞歸地構建一個對象.
English
Given a tuple type T that only contains string type, and a type U, build an object recursively.
type a = TupleToNestedObject<['a'], string>; // {a: string}
type b = TupleToNestedObject<['a', 'b'], number>; // {a: {b: number}}
type c = TupleToNestedObject<[], boolean>; // boolean. if the tuple is empty, just return the U type
答案
type TupleToNestedObject<T extends string[], U> = T extends [
infer L extends string,
...infer R extends string[]
]
? { [k in L]: R extends [] ? U : TupleToNestedObject<R, U> }
: U;