メニューに新しい項目を追加する

AddMenu.js

/**
 *@メニュー"MenuName"に"testFunc"を追加
 */
function addMenuTestFunc() {
    "use strict";
    var spreadsheetObj = SpreadsheetApp.getActiveSpreadsheet();
    var menuList       = [];
    menuList.push({
        name : "TestFunc",
        functionName : "testFunc"
    });
    spreadsheetObj.addMenu("MenuName", menuList);
}

AddMenus.js

/**
 *@メニュー"MenuName"に"testFunc"を追加
 */
function addMenuTestFunc() {
    "use strict";
    var spreadsheetObj = SpreadsheetApp.getActiveSpreadsheet();
    var menuList       = [];
    menuList.push({
        name : "TestFunc",
        functionName : "testFunc"
    });
        menuList.push({
        name : "TestFunc2",
        functionName : "testFunc2"
    });
    spreadsheetObj.addMenu("MenuName", menuList);
}