[UNTESTED!] For a Drupal GraphQL text field, get a wrapped string with its type (plain or html)

typedField.ts

/**
 * Determine the type of text from GraphQL.
 *
 * In the query, make sure to request all 3 subfields:
 *   my_field {
 *     processed
 *     format
 *     value
 *   }
 */
function typedField(field: unknown): { type: 'plain' | 'html'; value: string } {
  if (
    field &&
    typeof field === 'object' &&
    'format' in field &&
    typeof field.format === 'string'
  ) {
    if (
      field.format.endsWith('_html') &&
      'processed' in field &&
      typeof field.processed === 'string'
    ) {
      return { type: 'html', value: field.processed };
    }

    if ('value' in field) {
      return { type: 'plain', value: String(field.value) };
    }
  }

  // string, number, null, undefined, or something unrecognized
  return {
    type: 'plain',
    value: field === null || typeof field === 'undefined' ? '' : String(field),
  };
}

export default typedField;