Intersection.md

标题	标签
Intersection(求多个数组的交集)	extends,infer(继承,推断)

求多个数组的交集。

• 使用 infer 推断数组的每一项，从第一项开始，如果是数组则返回每一数组项，否则返回第一项，与剩余项求交集,否则返回 unknown。

代码如下:

type Intersection<T extends any[]> = T extends [infer F, ...infer R]
  ? (F extends any[] ? F[number] : F) & Intersection<R>
  : unknown;

使用方式:

type IntersectionRes1 = Intersection<[[1, 2], [2, 3], [2, 2]]>; //  2
type IntersectionRes2 = Intersection<[[1, 2, 3], [2, 3, 4], [2, 2, 3]]>; //  2 | 3
type IntersectionRes3 = Intersection<[[1, 2], [3, 4], [5, 6]]>; //  never
type IntersectionRes4 = Intersection<[[1, 2, 3], [2, 3, 4], 3]>; //  3
type IntersectionRes5 = Intersection<[[1, 2, 3], 2 | 3 | 4, 2 | 3]>; //  2 | 3
type IntersectionRes6 = Intersection<[[1, 2, 3], 2, 3]>; //  never

应用场景

如下所示,鼠标悬浮到对应的类型变量可以查看类型。