Google script to clean up root drive folder. All files are moved to their extension( mimetype) folder

Code.gs

/// returns extension from the file object
/// Queries the mimetype
const getExtension = function(file) {
  var mime = file.getMimeType()
  var docType = mime.split("/").pop()
  return docType.split(".").pop()
};


/// send an email to myself when any files are moved
const notify = function(moved, log) {
  MailApp.sendEmail({
    to: Session.getActiveUser().getEmail(),
    subject: `Clean Up Root Drive folder - ${moved} files move`,
    htmlBody: `The following files have been moved: ${log}`,
  });
}


/// main
function CleanUpRootDrive() {
  const rootFolder = DriveApp.getRootFolder()
  const folders = rootFolder.getFolders()
  const rootFiles = rootFolder.getFiles()
  
  // Create a fast lookup for foldername
  var folderNameMap = {}
  while(folders.hasNext()) {
    const folder = folders.next()
    folderNameMap[folder.getName()] = folder
  }
  
  // iterate to all files in the root folder
  // and move them to their extensions folder
  var moved = 0 
  var log = ""
  while(rootFiles.hasNext()) {
    const file = rootFiles.next()    
    var ext = getExtension(file)

    var folder = folderNameMap[ext]
    if( !folder ) {
      folder = rootFolder.createFolder(ext) 
      folderNameMap[ext] = folder
    }
    
    /// Only move the folder if current user is the owner
    if(file.getAccess(Session.getActiveUser()) == DriveApp.Permission.VIEW) {
      continue
    }     
    if(file.getAccess(Session.getActiveUser()) == DriveApp.Permission.COMMENT) {
      continue
    }         
    file.moveTo(folder)      
    log += `<br> - [${file.getName()}] moved to folder [${ext}].`
    moved ++
  }
  
  if(moved > 0 ) {
    notify(moved, log)
  }
}