Custom Script to add current date in Google Docs

currentDate.gs

function onOpen() {
  var ui = DocumentApp.getUi();
  // Or FormApp or SpreadsheetApp.
  ui.createMenu('Custom Scripts')
      .addItem('Insert Date', 'insertDate')
      .addToUi();
}

function insertDate() {
  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.
    const monthNames = ["January", "February", "March", "April", "May", "June",
                        "July", "August", "September", "October", "November", "December"];
      var d = new Date();
      var dd = d.getDate();
      var mm = d.getMonth();
      var yyyy = d.getFullYear();
      var date = monthNames[mm] + " " + dd + ", " + yyyy;
      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.');
  }
}