Extract all the non-png links from a directory of Markdown files

index.js

const markdownLinkExtractor = require('markdown-link-extractor')

const fs = require('fs')
const { join } = require('path')

const dir = join(__dirname, 'chapters')
const files = fs.readdirSync(dir)
const titles = files.map(
  file => file.substr(0, file.lastIndexOf('.')).split(' - ')[1],
)

const getMarkdown = f => fs.readFileSync(join(dir, f)).toString()

fs.writeFileSync(
  join(__dirname, 'links.md'),
  files
    .filter(f => !f.startsWith('.'))
    .map((f, i) => {
      const links = markdownLinkExtractor(getMarkdown(f))
      const fLinks = links.filter(url => url.substr(-3) !== 'png')

      if (!fLinks.length) return null

      return [`## ${titles[i]}`, fLinks.join('\n')].join('\n')
    })
    .filter(s => s !== null)
    .join('\n\n'),
  'utf8',
)