Google Script How do I getGivenName() of getActiveUser()

Question

Each user on the domain initiates a simple script we run for leave entitlements but we want the welcome message to be \"Hi First Name,\" however the script doesn\'t seem to

Answer 1

As noted in comments, and in Documentation, the UserManager Service is only accessible by Domain Administrators.

Here's an alternative. Domain Users may have themselves in their own contacts, so how about a best-effort attempt at finding themselves there?

/**
 * Get current user's name, by accessing their contacts.
 *
 * @returns {String} First name (GivenName) if available,
 *                   else FullName, or login ID (userName)
 *                   if record not found in contacts.
 */
function getOwnName(){
  var email = Session.getEffectiveUser().getEmail();
  var self = ContactsApp.getContact(email);

  // If user has themselves in their contacts, return their name
  if (self) {
    // Prefer given name, if that's available
    var name = self.getGivenName();
    // But we will settle for the full name
    if (!name) name = self.getFullName();
    return name;
  }
  // If they don't have themselves in Contacts, return the bald userName.
  else {
    var userName = Session.getEffectiveUser().getUsername();
    return userName;
  }
}