Convert a post type in Sanity.io to markdown files with frontmatter

sanityToMarkdownPosts.js

/* eslint-disable */
const fs = require('fs')
const sanityClient = require('@sanity/client')
const groq = require('groq')
const BlocksToMarkdown = require('@sanity/block-content-to-markdown')
const config = { projectId: '<YourID>', dataset: '<DatasetName>', useCdn: true }
const client = sanityClient(config)


const serializers = {
  types: {
    code: props => `\`\`\`${props.node.language}\n${props.node.code}\n\`\`\``,
    codesandbox: ({node}) => `<iframe src="https://codesandbox.io/embed/${node.id}?fontsize=14" style="width:100%; height:500px; border:0; border-radius: 4px; overflow:hidden;" sandbox="allow-modals allow-forms allow-popups allow-scripts allow-same-origin"></iframe>`,
    youtube: ({ node }) => `<iframe width="560" height="315" src="https://www.youtube.com/embed/${node.id}" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>`,
  },
  marks: {
    internalLink: props => `![${props.children[0]}](${props.mark.link})`
  }
}

async function getDocs() {
  const filter = '*[_type == "post" && defined(slug)]'
  const projection = groq`{
    _id,
    _type,
    "poster": poster.asset->url,
    title,
    blurb,
    slug,
    text[]{
      ...,
      children[]{
        ...,
        _type == "internalLink" => {
          "link": @->slug.current
        }
      }
    }
  }`
  const query = [filter, projection].join(' ')
  const docs = await client.fetch(query)
  docs.forEach(post => {
    const { title, blurb, text, slug } = post
    const content = `
---
layout: post
title: "${title}"
description: "${BlocksToMarkdown(blurb)}"
---

${BlocksToMarkdown(text, { serializers, projectId, dataset })}
`
    const filename = `posts/${post.slug.current}.md`
    fs.writeFile(filename, content, function(err) {
      if (err) {
        return console.log(err)
      }
      console.log('The file was saved!', filename)
    })
  })
}
getDocs()

Nevermind, figured it out! Uploaded here if anyone else if having problems with image export w/ block level content