Appearance
数组扁平化
arr: unknown[]
一层或多层嵌套的数组
打平之后的数组
import { flatten } from "poor-utils-pro"; flatten([1, 2, [5, [6, [7, [8]]]], 3, 4]) // [1, 2, 5, 6, 7, 8, 3, 4]