Webpack manifest generator hook that includes dependent chunks

generate-webpack-manifest.js

const getExtension = (file) => {
  if (/\.css$/.test(file)) {
    return 'css'
  }
  if (/\.js$/.test(file)) {
    return 'js'
  }

  return 'asset'
}
const mapFiles = (chunk, files) => {
  return chunk.files
    .map(file => files.filter(f => f.isChunk && !f.isAsync && f.chunk.name === chunk.name).map(file => file.path))
    .reduce((files, fileArray) => {
      return [...files, ...fileArray.filter(f => !files.includes(f))]
    }, [])
    .reduce((files, file) => {
      let ex = getExtension(file)
      files[ex] = files[ex] || []
      files[ex].push(file)
      return files
    }, {})
}

const mapChunks = (chunk, files) => {
  return Array.from(
    chunk.groupsIterable, 
    (group) => {
        return group.chunks.map(chunk => ({name: chunk.name, files: mapFiles(chunk, files)}))
    }
  ).reduce((list, entry) => {
    return [...list, ...entry]
  }, [])
}

module.exports = (seed, files) => {
  return files.reduce((manifest, {name, path, isChunk, isInitial, chunk}) => {
    let dependencies = []
    let groups = []

    if (isChunk) {
      dependencies = mapChunks(chunk, files)
    }

    return {...manifest, [name]: {path, dependencies}}

  }, seed)
}