Typescript类型体操 - Chunk
题目
中文
你知道 lodash 吗? lodash中有一个非常实用的方法Chunk, 让我们实现它吧.
Chunk<T, N>接受两个泛型参数, 其中 T 是 tuple 类型, N是大于 1 的数字
type exp1 = Chunk<[1, 2, 3], 2>; // expected to be [[1, 2], [3]]
type exp2 = Chunk<[1, 2, 3], 4>; // expected to be [[1, 2, 3]]
type exp3 = Chunk<[1, 2, 3], 1>; // expected to be [[1], [2], [3]]
English
Do you know lodash? Chunk is a very useful function in it, now let's implement it.
Chunk<T, N> accepts two required type parameters, the T must be a tuple, and the N must be an integer >=1
type exp1 = Chunk<[1, 2, 3], 2>; // expected to be [[1, 2], [3]]
type exp2 = Chunk<[1, 2, 3], 4>; // expected to be [[1, 2, 3]]
type exp3 = Chunk<[1, 2, 3], 1>; // expected to be [[1], [2], [3]]
答案
type Chunk<
T extends any[],
N extends number,
S extends any[] = [],
ALL extends any[] = []
> = T extends [infer L, ...infer R]
? S['length'] extends N
? Chunk<T, N, [], [...ALL, S]>
: Chunk<R, N, [...S, L], ALL>
: S['length'] extends 0
? []
: [...ALL, S];
