import { buildClient } from '@datocms/cma-client-node';
async function run() {
  const client = buildClient({ apiToken: '<YOUR_API_TOKEN>' });
  
  const fieldIdOrApiKey = 'blog_post::title';
  
  const field = await client.fields.duplicate(fieldIdOrApiKey);
  
  console.log(field);
}
run();

{
  id: '124',
  label: 'Title',
  field_type: 'string',
  localized: true,
  default_value: {
    en: 'A default value',
    it: 'Un valore di default'
  },
  api_key: 'title',
  hint: 'This field will be used as post title',
  validators: {
    required: {}
  },
  appearance: {
    editor: 'single_line',
    parameters: {
      heading: false
    },
    addons: [
      {
        id: '1234',
        field_extension: 'lorem_ipsum',
        parameters: {}
      }
    ]
  },
  position: 1,
  item_type: {
    type: 'item_type',
    id: '44'
  },
  fieldset: null
}