Generate default slug w/listener

default-slug.js

const {deburr, kebabCase} = require('lodash')
const sanityClient = require('@sanity/client')

const client = sanityClient({
  projectId: '<your priojectId>',
  dataset: '<your dataset>',
  token: '<your auth token>',
  useCdn: false
})

const SOURCE_FIELD = 'title'
const slugify = value => deburr(kebabCase(value))

client
  .listen(
    '*[_type == $type && !(_id in path("drafts.**"))]',
    {type: 'objectWithDefaultSlug'},
    {events: ['mutation']}
  )
  .subscribe(event => {
    const document = event.result
    // we only want to respond to appear transitions, and skip if source field is missing
    // or the slug is already set
    if (event.transition !== 'appear' || !document[SOURCE_FIELD] || document.slug) {
      return
    }

    // todo: make sure we generate an unique slug by querying the dataset for existing slugs
    client
      .patch(document._id)
      .set({slug: {_type: 'slug', current: slugify(document[SOURCE_FIELD])}})
      .commit()
  })