Get list of users Gmail messages Google Apps Script

Code.gs

function getMessages(includeSpamTrash, labelIds, query, callback) {
  var pageToken;
  var messages = [];
  do {
    var resp = Gmail.Users.Messages.list('me', {
      includeSpamTrash: includeSpamTrash,
      labelIds: labelIds,
      q: query,
      pageToken: pageToken
    });
    pageToken = resp.nextPageToken;
    if (resp.messages && resp.messages.length > 0) {
      messages = messages.concat(resp.messages.map(function(msg) {
        return msg.id;
      }));
    }
  } while (pageToken);
  callback(messages);
}