Google Apps Script Function to get the first gmail draft from your account and output its attributes.

get_first_gmail_draft_attributes.gs

function getFirstGmailDraftAttributes() {
  var draftThreads = GmailApp.search("in:drafts", 0, 1);
  
  if (draftThreads.length === 0) {
    Browser.msgBox("No drafts found.");
    return
  }
  
  var draft = draftThreads[0].getMessages()[0];
  
  var draftAttributes = {
    id: draft.getId(),
    subject: draft.getSubject(),
    to: draft.getTo(),
    cc: draft.getCc(),
    bcc: draft.getBcc(),
    body: draft.getBody(),
    attachments: draft.getAttachments()
  }
  
  return draftAttributes;
}

Example: Showing the subject for the first draft in your gmail account.

var draftSubject = getFirstGmailDraftAttributes().subject;
Browser.msgBox(draftSubject);