Creates a new menu in the Spreadsheet UI. Each menu entry runs a user-defined function.
var activeSheet = SpreadsheetApp.getActiveSpreadsheet();
var menuItems = [];
// When the user clicks on "addMenuExample" then "Menu 1", the function Myfunction1 is executed.
menuItems.push({name: "Menu 1", functionName: "Myfunction1"});
menuItems.push(null); // adding line separator
menuItems.push({name: "Menu 2", functionName: "Myfunction2"});
activeSheet.addMenu("addMenuExample", menuEntries);