将格式化的int保存到firestore以用于Javascript

我有一个函数，它应该返回这样的格式

2.3mb

function formatSize(bytes) {
  var kb = 1024;
  var ndx = Math.floor(Math.log(bytes) / Math.log(kb));
  //var fileSizeTypes = ["bytes", "kb", "mb", "gb", "tb", "pb", "eb", "zb", "yb"];
  var size = (bytes / kb / kb).toFixed(2);
  var sizeInString = size.toString() + 'mb';
  return sizeInString;
} // This is just a sample script. Paste your real code (javascript or HTML) here.

if ('this_is' == /an_example/) {
  of_beautifier();
} else {
  var a = b ? (c % d) : e[f];
}

当我尝试将其放入firestore时，它返回一个错误

Uncaught (in promise) Error: Function DocumentReference.set() called with invalid data. Unsupported field value: undefined (found in field size)

其余的是：

var fileSize = formatSize(fileN[0].size);

及

---

为什么firestore无法保存该字段。

发现问题在于函数之间的参数传递错误，导致变量无法获取最上面的值

function putMessage(fileName, fileSize) {
  db.collection("user").doc("document").collection('occur').add({
      name: fileName,
      size: fileSize,
    })
    .then(function(docRef) {
      console.log("Document written");
    })
    .catch(function(error) {
      console.error("Error putting Message:", error);
    });
}