遍历JSON对象时，循环缺少值

Question

我想遍历对象数组，并将所有1 ^st 和2 ^nd 值从上到下依次放入数组。

返回的数组应该包含31个元素，但是我在下面编写的解决方案返回array.length == 29。我找不到循环在哪里丢失值。

let userTree = [{
  "username": "USER1",
  "income": 1000,
  "st1": {
    "username": "USER2",
    "income": 2000,
    "st1": {
      "username": "USER4",
      "income": 4564560,
      "st1": '',
      "nd2": {
        "username": "USER7",
        "income": 4564560,
        "st1": {
          "username": "USER10",
          "income": 4564560,
          "st1": '',
          "nd2": ''
        },
        "nd2": {
          "username": "USER11",
          "income": 4564560,
          "st1": '',
          "nd2": ''
        }
      }
    },
    "nd2": ''
  },
  "nd2": {
    "username": "USER3",
    "income": 2001,
    "st1": {
      "username": "USER5",
      "income": 40,
      "st1": '',
      "nd2": ''
    },
    "nd2": {
      "username": "USER6",
      "income": 4564560,
      "st1": {
        "username": "USER8",
        "income": 40,
        "st1": '',
        "nd2": {
          "username": "USER12",
          "income": 40,
          "st1": '',
          "nd2": ''
        }
      },
      "nd2": {
        "username": "USER9",
        "income": 40,
        "st1": {
          "username": "USER13",
          "income": 40,
          "st1": '',
          "nd2": ''
        },
        "nd2": {
          "username": "USER14",
          "income": 40,
          "st1": '',
          "nd2": ''
        }
      }
    }
  }
}];


let userArray = [userTree[0]];
let counter = 1;
let rowArray = [];
let counterArr = [];
let usersRow = '';
let rowHTML = '';
let treeRow = '';

const getUsers = (users = {}) => {
  Object.entries(users).forEach(user => {
    let key = user[0];
    let value = user[1];
    if (typeof value == 'object') {
      userArray.push(value);
    } else if (value == '') {
      userArray.push(value);
    }
  });
};


const getSubUsers = (subUser = {}) => {
  for (let i = 0; i <= userArray.length; i++) {
    let lastUser = userArray[i];
    getUsers(lastUser);
  }
};

getSubUsers(userArray);

console.log(userArray.length);

console.log(userArray);