stacker.news/lib/md.js

import { gfmFromMarkdown } from 'mdast-util-gfm'
import { visit } from 'unist-util-visit'
import { gfm } from 'micromark-extension-gfm'
import { fromMarkdown } from 'mdast-util-from-markdown'

export function mdHas (md, test) {
  if (!md) return []
  const tree = fromMarkdown(md, {
    extensions: [gfm()],
    mdastExtensions: [gfmFromMarkdown()]
  })

  let found = false
  visit(tree, test, () => {
    found = true
    return false
  })

  return found
}

export function extractUrls (md) {
  if (!md) return []
  const tree = fromMarkdown(md, {
    extensions: [gfm()],
    mdastExtensions: [gfmFromMarkdown()]
  })

  const urls = new Set()
  visit(tree, ({ type }) => {
    return type === 'link' || type === 'image'
  }, ({ url }) => {
    urls.add(url)
  })

  return Array.from(urls)
}

export const quote = (orig) =>
  orig.split('\n')
    .map(line => `> ${line}`)
    .join('\n') + '\n'