Cannot assign to read only property 'product' of object '#<WorkerNavigator>' initializeCore.js line 176

Description

I’ve updated my app from react-native 0.34 to 0.37. Then when launching the app I encounter: Cannot assign to read only property 'product' of object '#<WorkerNavigator>' initializeCore.js line 176

Now I realize that nearly no-one is going to be able to reproduce this as it is most probably a clash with one of the modules I use. Here is my package.json:

"dependencies": {
    "lodash": "^4.16.6",
    "moment": "^2.15.1",
    "ramda": "^0.22.1",
    "react": "^15.3.2",
    "react-native": "^0.37.0",
    "react-native-accordion": "^1.0.1",
    "react-native-button": "^1.7.0",
    "react-native-invertible-scroll-view": "^1.0.0",
    "react-native-maps": "^0.11.0",
    "react-native-modal-picker": "0.0.16",
    "react-native-pullable-view": "^1.0.2",
    "react-native-router-flux": "^3.37.0",
    "react-native-theme-picker": "^1.0.0",
    "react-native-vector-icons": "^3.0.0",
    "react-redux": "^4.4.5",
    "redux": "^3.6.0",
    "redux-persist": "^4.0.0-alpha5",
    "redux-thunk": "^2.1.0",
    "tcomb-form-native": "^0.6.1",
    "uuid": "^2.0.3"
  },
  "devDependencies": {
    "babel-preset-react-native": "^1.9.0",
    "babel-register": "^6.14.0",
    "remote-redux-devtools": "^0.5.3",
    "remote-redux-devtools-on-debugger": "^0.6.3",
    "tap-spec": "^4.1.1",
    "tape": "^4.6.0"
  }

But I think that we have a bug in the code and here is why. I did launch a new project with react-native init awesomeApp

The awesomeApp launched without error, unlike the app that I updated. However if you do console.log(global.navigator)in the render function of that dummy app I see that the product property hasn’t changed to ReactNative. For me it stays “gecko”.

I downgraded my app to 0.36.0 and it’s not crashing. The new code in intializeCore has been pushed with this commit: https://github.com/facebook/react-native/commit/606fc1148709357c3da9fb5bc45abaa251205378

if I change navigator.product = 'ReactNative'; to Object.defineProperty(navigator, 'product', {value: 'ReactNative'}); (as it was before)

then my app doesn’t crash on 0.37 and the output of console.log(global.navigator) is product = ‘ReactNative’ both in my app and in the dummy app.

Reproduction

1. Clone this repository: https://github.com/compojoom/bugreactnative launch the app as usual - npm install and then launch it with xdebug.

Enable remote debugging and look at the console output - it should say “Gecko” instead of “ReactNative”

If you change the code in node_modules/react-native/Libraries/Core/InitializeCore.js on line 176 to: Object.defineProperty(navigator, 'product', {value: 'ReactNative'});

then the output in the console should read “ReactNative”

Additional Information

• React Native version: 0.37

• Platform: iOS (possible on android as well)

• Operating System: MacOS

• works as expected with react native version: 0.36

If you also consider this a bug I would be happy to make a pull request.

[ide]

We don’t want to return Gecko probably. Something like this seems like what we want:

 Object.defineProperty(GLOBAL.navigator, 'product', {
  enumerable: true,
  configurable: true,
  get() { return 'ReactNative'; },
  set(value) {}
})

[compojoom]

Ok, I thought about the same. I’ll do a PR tomorrow.