gz.js

'use strict'

const fs = require('fs')
const path = require('path')
const zlib = require('zlib')

require.extensions['.gz'] =
require.extensions['.js.gz'] = (module, filename) => {
  if (path.extname(filename.slice(0, -3)) === '.js') {
    let content = zlib.unzipSync(fs.readFileSync(filename)).toString()
    content = content.charCodeAt(0) === 0xFEFF ? content.slice(1) : content
    module._compile(content, filename)
  }
}

require.extensions['.js'] = ((func) => (module, filename) => {
  const gz = filename + '.gz'
  return fs.existsSync(gz) ? require.extensions['.gz'](module, gz) : func(module, filename)
})(require.extensions['.js'])