.getEditors() returns 'DriveUser,DriveUser' - google-apps-script

Question

Before adding new editors to a Google drive folder, I'd like to check first which ones already exist in that folder's editors. This is to avoid unnecessary share notification if user is already an existing editor.
However, .getEditors() always returns 'DriveUser,DriveUser' so all editors get added even if existing already.
Thanks to advise if you have a solution to this.
Here's my code:
var dropboxID = "zzxxccvv112233";
var folderList = DriveApp.getFolderById(dropboxID).getFoldersByName(employee);
if (folderList.hasNext()) {
var employeeFolder = folderList.next(); //folder already exists so just add new Editors, if any
var currentEditors = employeeFolder.getEditors();
Logger.log("currentEditors = " + currentEditors);
var newEditors = emailTo + "," + emailCc;
newEditors = newEditors.replace(/\s/g, '');
newEditors = newEditors.split(',');
var editorsToAdd = [];
for (var i=0 ; i<newEditors.length ; i++) {
if (currentEditors.indexOf(newEditors[i]) < 0) {
editorsToAdd.push(newEditors[i]);
}
}
employeeFolder.addEditors(editorsToAdd);
} else {
and Logger shows this:
[20-03-05 21:23:46:637 HKT] currentEditors = DriveUser,DriveUser

Answer 1

You should be comparing by email address with User.getEmail()
// Get all of the current editor emails in one array
var currentEditorEmails = currentEditors.map(function (editor) { return editor.getEmail() });
// Check if the new editor emails exist in the currentEditorEmails array
for (var i=0 ; i<newEditors.length ; i++) {
if (currentEditorEmails.indexOf(newEditors[i]) < 0) {
editorsToAdd.push(newEditors[i]);
}
}
If you're using V8, you could use an arrow function instead.
const currentEditorEmails = currentEditors.map(editor => editor.getEmail());