JSON Metafield

index.html

<script src="https://unpkg.com/cosmicjs@3.0.1/cosmicjs.browser.min.js"></script>
<script>
  var api = new Cosmic();
  var bucket = api.bucket({
    slug: 'json-bucket'
  })
  bucket.addObject({
    title: 'Test Page',
    type_slug: 'pages',
    metafields: [
      {
        type: 'json',
        key: 'json_data',
        title: 'JSON Data',
        value: {
          test: true,
          arrays: [1,2,3],
          nested_objects: {
            this: 'that',
            the_other: 'another'
          }
        }
      }
    ]
  }).then(data => {
    console.log(data)
  })
</script>