rsnext/examples/cms-sanity/lib/sanity.js

import sanityClient from '@sanity/client'

const options = {
  // Find your project ID and dataset in `sanity.json` in your studio project
  dataset: 'production',
  projectId: process.env.NEXT_EXAMPLE_CMS_SANITY_PROJECT_ID,
  useCdn: process.env.NODE_ENV === 'production',
  // useCdn == true gives fast, cheap responses using a globally distributed cache.
  // Set this to false if your application require the freshest possible
  // data always (potentially slightly slower and a bit more expensive).
}

export default sanityClient(options)
export const previewClient = sanityClient({
  ...options,
  useCdn: false,
  token: process.env.NEXT_EXAMPLE_CMS_SANITY_API_TOKEN,
})