javascript 2階層あるjsonデータを1次元配列として出力する

const json = '{"hoge1":1,"hoge2":{"foo1":"bbb","foo2":"ccc","foo3":"ddd"},"hoge3":"eee"}';

const x = JSON.parse(json);

let arr = [];

for (let key in x) {

  if ('' + x[key] === x[key] || 0 + x[key] === x[key]) { // 文字列（値）か数値であれば
    
    arr.push([key, x[key]]);

  } else {// 文字列か数値でなければ

    for (let key2 in x[key]) {
      if ('' + x[key][key2] == x[key][key2] ||  0 + x[key][key2] == x[key][key2]) {
        arr.push([key2, x[key][key2]]);
      }
    }
  }
}

console.log(arr);