standard-markdown/index.js

const standard = require('standard')
const fs = require('fs')
const range = require('lodash.range')
const flatten = require('lodash.flatten')
const async = require('async')
const blockOpener = /^```(js|javascript)$/mg
const blockCloser = /^```$/mg

let standardMarkdown = module.exports = {}

standardMarkdown.lintText = function (text, done) {
  const blocks = extractCodeBlocks(text)
  async.map(
    blocks,
    function (block, callback) { return standard.lintText(block, callback) },
    function (err, results) {
      if (err) return done(err)
      results = results.map(r => r.results.map(res => res.messages))
      results = flatten(flatten(results))
      return done(null, results)
    }
  )
}

standardMarkdown.lintFiles = function (files, done) {
  async.map(
    files,
    function (file, callback) {
      standardMarkdown.lintText(fs.readFileSync(file, 'utf8'), function (err, errors) {
        if (err) return callback(err)
        return callback(null, {file: file, errors: errors})
      })
    },
    function (err, results) {
      if (err) return done(err)
      return done(null, results)
    }
  )
}

function extractCodeBlocks (text) {
  const lines = text.split('\n')
  const matches = text.match(blockOpener) || []
  return range(matches.length).map(index => extractCodeBlock(lines, index))
}

// Seek out the nth block of javascript code in the file
function extractCodeBlock (lines, targetIndex) {
  let currentIndex = 0
  let insideBlock = false
  return lines
    .map(line => {
      // standard doesn't like trailing whitespace
      line = line.replace(/\s*$/, '')

      if (line.match(blockOpener)) {
        if (currentIndex === targetIndex) {
          insideBlock = true
          line = `// -${line}`
        }
        currentIndex++
      }
      if (line.match(blockCloser)) insideBlock = false
      if (!insideBlock) line = `// -${line}`
      return line
    })
    .join('\n')
    .concat('\n') // standard requires a newline at end of file
}