perparePosts.js

const transformPosts = posts => posts.map(post => {
  delete post._links
  delete post.guid
  delete post.excerpt
  delete post.author
  delete post.comment_status
  delete post.ping_status
  delete post.template
  delete post.format
  delete post.meta
  delete post.status
  delete post.type
  post.publishDate = post.date_gmt + '+00:00'
  delete post.date_gmt
  delete post.date
  delete post.modified
  delete post.modified_gmt
  delete post.tags
  delete post.sticky
  post.body = `<div>${post.content.rendered}</div>`
  delete post.content
  post.title = post.title.rendered
  post.slug = post.slug
  post.category = post.categories[0]
  delete post.categories
  return extractBodyImages(post)
})

const extractBodyImages = post =>{
  const regex = /<img.*?src="(.*?)"[\s\S]*?alt="(.*?)"/g
  post.bodyImages = []
  while (foundImage = regex.exec(post.body)) {
    const alt = foundImage[2] ? foundImage[2].replace(/_/g, ' ') : ''
    post.bodyImages.push({
      link: foundImage[1],
      description: alt,
      title: alt,
      postId: post.id
    })
  }
  return post
}