index.js

'use strict'
const fs = require('fs')
const path = require('path')
const glob = require('glob')
const swPrecache = require('sw-precache')

function getOutputs (output) {
  return new Promise((resolve, reject) => {
    fs.stat(output, async (error, stats) => {
      if (!fs.existsSync(output) || error) {
        console.log('[error] Not found')
        process.exit(2)
      }

      const assets = stats.isDirectory()
        ? await getFiles(output + '/**/*.{css,js}')
        : await getFiles(path.dirname(output) + '/**/*.{css,js}')
      const base = stats.isDirectory() ? output : path.dirname(output)
      const htmls = stats.isDirectory()
        ? await getFiles(output + '/**/*.html')
        : [output]

      resolve({ assets, base, htmls })
    })
  })
}

function getFiles (path) {
  return new Promise((resolve, reject) => {
    glob(path, (err, data) => resolve(data))
  })
}

function hashFile (hash, file) {
  return `${path.dirname(file)}/${path.basename(
    file,
    path.extname(file),
  )}-${hash + path.extname(file)}`
}

module.exports = async options => {
  const { assets, base, htmls } = await getOutputs(options[0])
  const hash = +new Date()

  Promise.all([
    htmls.map(html =>
      fs.readFile(html, 'utf-8', (error, data) => {
        if (error) throw error

        const htmlBefore = '</body>'
        const htmlAfter =
          '<script src="service-worker.js"></script><script>if("serviceWorker" in navigator && window.location.protocol === "https:")navigator.serviceWorker.register("/service-worker.js")</script></body>'

        fs.writeFile(
          html,
          data.replace(htmlBefore, htmlAfter),
          (error, data) => {
            if (error) throw error
            console.info(`${html} was saved!`)
          },
        )
      }),
    ),

    assets.map(asset =>
      fs.readFile(asset, 'utf-8', (error, data) => {
        if (error) throw error

        htmls.map(html =>
          fs.readFile(html, 'utf-8', (error, data) => {
            if (error) throw error

            const assetBefore = path.basename(asset)
            const assetAfter = `${path.basename(
              asset,
              path.extname(asset),
            )}-${hash + path.extname(asset)}`

            fs.writeFile(
              html,
              data.replace(assetBefore, assetAfter),
              (error, data) => {
                if (error) throw error
              },
            )
          }),
        )

        fs.writeFile(hashFile(hash, asset), data, (error, data) => {
          if (error) throw error

          fs.unlink(asset, (error, data) => {
            if (error) throw error
            console.info(`${hashFile(hash, asset)} was saved!`)
          })
        })
      }),
    ),

    swPrecache.write(`${base}/service-worker.js`, {
      staticFileGlobs: [
        base +
          '/**/*.{html,js,css,png,jpg,jpeg,gif,svg,ico,eot,ttf,woff,woff2,txt,webapp,json}',
      ],
      stripPrefix: base,
    }),
  ])
}