split-require returns empty object when minfied

[m90]

I'm seeing some really strange behavior when using split-require together with tinyify. I am trying to conditionally load a large library for browser that don't support window.crypto.subtle like this:

var splitRequire = require('split-require')

module.exports = bindCrypto

var cryptoProvider = window.crypto && window.crypto.subtle
  ? getWebCrypto()
  : getForgeCrypto()

function bindCrypto (consumerFn) {
  return function () {
    var args = [].slice.call(arguments)
    return cryptoProvider
      .then(function (cryptoImplementation) {
        return consumerFn.apply(cryptoImplementation, args)
      })
  }
}

function getWebCrypto () {
  return Promise.resolve(require('./web-crypto'))
}

function getForgeCrypto () {
  return new Promise(function (resolve, reject) {
    splitRequire('./forge-crypto', function (err, forgeCrypto) {
      if (err) {
        return reject(err)
      }
      resolve(forgeCrypto)
    })
  })
}

This works as expected, but strangely I noticed that some time early September 2020 it looks like the splitRequire call passes an empty object ({}) to the function instead of the module's export.

However this only happens when I apply tinyify to the code above. If I leave it unminified, I will be passed the correct export. It does not seem to matter if the chunk that is split off is minified or not.

Quite frankly, this does not make any sense to me considering that it used to work and broke without any intervention (I am aware of) apparently, so I would be happy if anyone has any hint about how to even debug this?

For the sake of completeness this is how I bundle things:

var transforms = JSON.parse(JSON.stringify(pkg.browserify.transform))
var b = browserify({
  entries: './index.js',
  // See: https://github.com/nikku/karma-browserify/issues/130#issuecomment-120036815
  postFilter: function (id, file, currentPkg) {
    if (currentPkg.name === pkg.name) {
      currentPkg.browserify.transform = []
    }
    return true
  },
  transform: transforms.map(function (transform) {
    if (transform === '@offen/l10nify') {
      return ['@offen/l10nify', { locale: locale }]
    }
    return transform
  })
})

b.on('split.pipeline', function (pipeline) {
  tinyify.applyToPipeline(pipeline)
})

return b
  .exclude('dexie')
  .plugin('tinyify') // commenting out this line makes things work, but I end up with non-minified code
  .plugin('split-require', {
    dir: dest,
    filename: function (entry) {
      return 'chunk-' + entry.index + '.js'
    },
    sri: 'sha384',
    output: function (bundleName) {
      var buf = ''
      return to(onwrite, onend)

      function onwrite (chunk, enc, cb) {
        buf += chunk
        cb()
      }

      function onend (cb) {
        var hash = crypto.createHash('sha1').update(buf)
        var name = bundleName.replace(/\.js$/, '') + '-' + hash.digest('hex').slice(0, 10) + '.js'
        this.emit('name', name)
        fs.writeFile(dest + name, buf, cb)
      }
    }
  })
  .bundle()
  .pipe(source('index.js'))
  .pipe(buffer())
  .pipe(gap.prependText('*/'))
  .pipe(gap.prependFile('./../banner.txt'))
  .pipe(gap.prependText('/**'))
  .pipe(rev())
  .pipe(gulp.dest(dest))
  .pipe(rev.manifest(dest + 'rev-manifest.json', { base: dest, merge: true }))
  .pipe(gulp.dest(dest))

[m90]

This seems to be the relevant portion of the code when minified:

    var ze = function(e) {
        return function() {
            var t = [].slice.call(arguments);
            return Le.then(function(n) {
                return e.apply(n, t)
            })
        }
    }
      , Le = window.crypto && window.crypto.subtle ? Promise.resolve(je) : new Promise(function(e, t) {
        i(163, function(n, r) { // n is null, r is {} when putting a breakpoint here
            if (n)
                return t(n);
            e(r)
        })
    }
    )

[goto-bus-stop]

hmm my guess would be that common-shakeify (part of tinyify) can't see through the splitRequire call and decides that every export in ./forge-crypto is unused. I don't immediately have a good idea how to fix that—the best approach for now may be to use the individual modules included in tinyify (except common-shakeify) and see if that works out.

[m90]

the best approach for now may be to use the individual modules included in tinyify (except common-shakeify) and see if that works out.

This actually works as expected. I still don't fully understand how it worked earlier this year, but maybe I can find out something after some more spelunking.

Thanks for the hint!

[m90]

It looks like this change: digitalbazaar/forge@0.9.1...0.10.0 which fixed a CVE broke it (i.e. made common-shakeify eat the exports). There are changes in the webpack setup which I would think made the difference, but then again I have no idea how webpack works ...