Google Apps Script Convert Array of Users to Array of Email Addresses

Question

I'm trying to write a script in Google Apps Script.

I need to check if a user with an email user@domain.com is a viewer or editor of a folder. If the users is neither a viewer or editor I want to add that user as a viewer.

I'm using getViewers to get an array of viewers.

https://developers.google.com/apps-script/reference/drive/folder#getViewers()

There is no way as far as I can tell to look up user by email address, only email address by user: https://developers.google.com/apps-script/reference/drive/user#getEmail()

So I need to convert the array of viewers (users) to array of email addresses. Then I can use indexOf to check if user@domain.com is on that list.

How do I do that? From what I understand I need to use call or apply to apply a class to an array and get another array.

By the way I realize that this works, but I'm wondering if there is a faster or cleaner way to do it without having to loop through the array:

       var vieweremails = new Array();
    var viewers = folder.getViewers().concat(folder.getEditors()).concat(folder.getOwner()); 

   for (var i = 0; i < viewers.length; i++) {
   vieweremails[i] = viewers[i].getEmail()
 }

Answer 1

If you want to check the new user email with all the viewers emails, there is no other way other than looping through the array. Instead you can use addViewer(emailAddress) , as it has no effect if the user was already on the list of editors.

Hope that helps!