如何将嵌套的JavaScript对象转换为平面数组？

function flattenObject(obj) {
  let result = {};

  function recurse(cur, prop) {
    if (Object(cur) !== cur) {
      result[prop] = cur;
    } else if (Array.isArray(cur)) {
      for (let i = 0, l = cur.length; i < l; i++) {
        recurse(cur[i], prop + "[" + i + "]");
      }
      if (l === 0) {
        result[prop] = [];
      }
    } else {
      let isEmpty = true;
      for (let p in cur) {
        isEmpty = false;
        recurse(cur[p], prop ? prop + "." + p : p);
      }
      if (isEmpty && prop) {
        result[prop] = {};
      }
    }
  }

  recurse(obj, "");
  return result;
}

const nestedObj = {
  a: 1,
  b: {
    c: 2,
    d: {
      e: 3,
      f: [4, 5, 6],
    },
  },
};

const flattenedArray = flattenObject(nestedObj);
console.log(flattenedArray);

{
  "a": 1,
  "b.c": 2,
  "b.d.e": 3,
  "b.d.f[0]": 4,
  "b.d.f[1]": 5,
  "b.d.f[2]": 6
}