嵌套数组中的Flattern对象Javascript

function flattenObject(arr) {
  var result = {};

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

  recurse(arr, '');
  return result;
}

var nestedArray = [1, [2, [3, 4], 5], 6];
var flattenedObject = flattenObject(nestedArray);
console.log(flattenedObject);

{
  '0': 1,
  '1[0]': 2,
  '1[1][0]': 3,
  '1[1][1]': 4,
  '1[2]': 5,
  '2': 6
}