index-revision-replace.js

'use strict'

const fs = require('fs')
const path = require('path')
const { createHash } = require('crypto')

class IndexRevision {
  apply(compiler) {
    compiler.hooks.done.tap('IndexRevisionReplace', () => {
      const builtServiceWorkerPath = path.resolve('build/service-worker.js')
      const _indexHtmlPath = path.resolve('build/_index.html')

      try {
        const _indexSrcCode = fs.readFileSync(_indexHtmlPath, 'utf-8')
        const _indexHashRaw = md5(_indexSrcCode)
        const _indexHashAsString = `"${_indexHashRaw}"`

        let serviceWorkerCode = fs.readFileSync(builtServiceWorkerPath, 'utf-8')
        serviceWorkerCode = serviceWorkerCode.replace('self._INDEX_HASH', _indexHashAsString)

        fs.writeFileSync(builtServiceWorkerPath, serviceWorkerCode)
      } catch (error) {
        console.log(
          `Failure in index-revision-replace.js. Almost always this is because of another failure in compilation. 
Look for and fix other errors before addressing _index.html not found:`,
          error.message,
          '\n'
        )
      }
    })
  }
}

function md5(input) {
  const hash = createHash('md5')
  return hash.update(input, 'utf-8').digest('hex')
}

module.exports = IndexRevision