Google Docs Script Macro: Insert Date

InsertDate.gs

/**
 * The onOpen function runs automatically when the Google Docs document is
 * opened. Use it to add custom menus to Google Docs that allow the user to run
 * custom scripts. For more information, please consult the following two
 * resources.
 *
 * Extending Google Docs developer guide:
 *     https://developers.google.com/apps-script/guides/docs
 *
 * Document service reference documentation:
 *     https://developers.google.com/apps-script/reference/document/
 */
function onOpen() {
  // Add a menu with some items, some separators, and a sub-menu.
  DocumentApp.getUi().createMenu('Utilities')
      .addItem('Insert Date', 'insertAtCursor')
      .addToUi();
}




/**
 * Inserts the sentence "Hey there!" at the current cursor location in boldface.
 */
function insertAtCursor() {
  var cursor = DocumentApp.getActiveDocument().getCursor();

  if (cursor) {
    // Attempt to insert text at the cursor position. If insertion returns null,
    // then the cursor's containing element doesn't allow text insertions.
    var date = Utilities.formatDate(new Date(), "GMT", "yyyy-MM-dd"); // "yyyy-MM-dd'T'HH:mm:ss'Z'"
    var element = cursor.insertText(date);
    if (element) {
      element.setBold(true);
    } else {
      DocumentApp.getUi().alert('Cannot insert text at this cursor location.');
    }
  } else {
    DocumentApp.getUi().alert('Cannot find a cursor in the document.');
  }
}

I Google Spreadsheet it raises an error: Cannot call DocumentApp.getUi() from this context. (line 17, file "Date Macro")

This works really well. Been looking for a way to output the day too. For example Monday. the formatDate does not seem to support dddd for day.

Would you be able to update the code so it outputs the weekday "name" too?

Thanks for this.

Doesn't work for me in Google Docs. I followed this:
https://webapps.stackexchange.com/questions/58965/is-there-a-way-to-insert-today-s-date-into-a-google-docs