Error while transforming with RN 0.64 and Typescript

[Marco Postigo Perez]

Just updated to new React Native version and it's broken again.

Output:

error app/sampleFile.ts: function (prevType) {
  this.state.exprAllowed = false;

  if (prevType === types._let || prevType === types._c...<omitted>...
} could not be cloned.
Error: function (prevType) {
  this.state.exprAllowed = false;

  if (prevType === types._let || prevType === types._c...<omitted>...
} could not be cloned.
    at Object.serialize (v8.js:202:7)
    at _default (/home/sample/app/node_modules/metro-transform-worker/node_modules/@babel/core/lib/transformation/util/clone-deep.js:18:30)
    at normalizeFile (/home/sample/app/node_modules/metro-transform-worker/node_modules/@babel/core/lib/transformation/normalize-file.js:52:36)
    at normalizeFile.next (<anonymous>)
    at run (/home/sample/app/node_modules/metro-transform-worker/node_modules/@babel/core/lib/transformation/index.js:31:50)
    at run.next (<anonymous>)
    at /home/sample/app/node_modules/metro-transform-worker/node_modules/@babel/core/lib/transform-ast.js:20:41
    at Generator.next (<anonymous>)
    at evaluateSync (/home/sample/app/node_modules/gensync/index.js:251:28)

Already updated my fork appropriately and it works with updated dependencies (+ necessary code changes). PR will be created soon.

[Geraint White]

@mppperez is your fork available on npm?

[Marco Postigo Perez]

Unfortunately not. You will have to include it manually if you want to use it. I guess with our next release we will drop this dependency as well and will check out the solution of directly use javascript-obfuscator.

We've got Hermes enabled (this should generate bytecode rather than JS) but we still have the JS files that need obfuscating... this may be already the solution even for others. I guess our configuration is just not completed yet.

[Geraint White]

I ended up publishing your fork to a private npm registry and it works well alongside Hermes. A solution using javascript-obfuscator directly would be interesting.

[A]

@mppperez @grit96 How did you manage to get hermes working with the obfuscator?
Either I obfuscate or I use hermes, I cannot get both to work.

More specifically, the obfuscator seems to work but then hermes recreates its own android.bundle without the obfuscation.

When I disassemble the bundle I get all the original code back. Any tips? ☹️

[Geraint White]

This is now the recommended way to do it:

// metro.config.js

module.exports = {
    transformer: {
      minifierPath: require.resolve('metro-minify-terser')
    }
}

[A]

@grit96 Thanks! I will try. One question: is it possible to plug in the javascript obfuscator there?

[A]

As an update, that still doesn't seem to minify my bundle. I am using hermes and this command to make a build:

react-native bundle --dev false --platform android --entry-file index.js --bundle-output ./android/app/src/main/assets/index.android.bundle --assets-dest ./android/app/src/main/res && rm -rf android/build/ && rm -rf android/app/build/ && rm -rf android/app/src/main/res/drawable* && mkdir -p android/app/build/intermediates/assets/release/ && cd android && ./gradlew assembleRelease && cd .."

But the index.android.bundle is still not obfuscated (I still get lots of "Original Name: xxx" which contains the original function names.)

Thoughts?
I have a feeling something is undoing the obfuscation step.