import { buildClient } from '@datocms/cma-client-node';
async function run() {
  const client = buildClient({ apiToken: '<YOUR_API_TOKEN>' });
  
  const menuItem = await client.menuItems.create({
    label: 'Posts',
    external_url: '',
    position: 1,
    open_in_new_tab: true,
    item_type: {
      type: 'item_type',
      id: '44'
    },
    parent: null
  });
  
  console.log(menuItem);
}
run();

{
  id: '34',
  label: 'Posts',
  external_url: '',
  position: 1,
  open_in_new_tab: true,
  item_type: {
    type: 'item_type',
    id: '44'
  },
  parent: null,
  children: [
    {
      type: 'menu_item',
      id: '34'
    }
  ]
}