将数组平铺到指定深度

const flatten = (arr, depth = 1) =>
  depth != 1
    ? arr.reduce((a, v) => a.concat(Array.isArray(v) ? flatten(v, depth - 1) : v), [])
    : arr.reduce((a, v) => a.concat(v), [])

标签：isArray,平铺,arr,reduce,depth,flatten,数组,深度,concat
来源： https://www.cnblogs.com/wuqilang/p/15103890.html