Can’t find variable: Symbol

[sm2017]

"Debug JS Remotely" is very buggy system , I have many issue with it

I use Symbol in a js file from 6 months ago , Today react-native told me

Can’t find variable: Symbol

Cannot find what?! Why you could find it yesterday?!

After hours of hard working and searching, I found that my codes works on iOS , but don't works in my and other machine (So there is no cache issue) that run-android

Suddenly I see https://medium.com/@jordan_mohi/cant-find-variable-symbol-in-react-native-782489d86bd7

OH!!! MY GOD!!!!! Debug JS Remotely !!! 😡

See also #15497 (I don't know why no body care it)

I open dev menu and press Debug JS Remotly , my code works

React Can find Symbol 😮 😲 😵 😳

[radko93]

@facebook-github-bot no-template

[facebook-github-bot]

Hey, thanks for reporting this issue! It looks like your description is missing some necessary information, or the list of reproduction steps is not complete. Can you please add all the details specified in the Issue Template? This is necessary for people to be able to understand and reproduce the issue being reported. I am going to close this, but feel free to open a new issue with the additional information provided. Thanks! See "What to Expect from Maintainers" to learn more.

[sm2017]

💩💩💩💩💩💩💩

#15497 has template

[sm2017]

I open #15805

[rottenoats]

Was getting the same error when using mobx for android.

Solution:
https://github.com/react-community/jsc-android-buildscripts#how-to-use-it-with-my-react-native-app

[Tai13492]

You should try
npm install --save es6-symbol
Then,
import 'es6-symbol/implement';
At the starting point of your project (App.js/index.js).
This will solve your problem but it may lead you to another problem if you are using mobx in your project.
The way to solve it is to downgrade your mobx version to 4.x.x (mobx version >= 5 will crash)
Hope this helps.

[badarshahzad]

Does their exist any other solution?

[newyankeecodeshop]

Using the upgraded jsc-android is your bet because it has the same runtime support as iOS 10+. You'll get a more consistent runtime experience.

[badarshahzad]

Where this could be find?

[newyankeecodeshop]

@badarshahzad Instructions are here: https://github.com/react-community/jsc-android-buildscripts#how-to-use-it-with-my-react-native-app
If you don't want to bump the minSdkVersion to 21 for that version of JSC (it includes 64-bit support), then you can use [email protected]. We've been using that version in two production apps targeting Android 17+ and it has been flawless.

[badarshahzad]

Thank you to suggest this one but I face this error when I used MobX instead of Redux. I am junior so kindly enlighten me what to do now.

[stevefan1999-personal]

Try this, it is very simple:

1. Install babel-polyfill and proxy-polyfill
2. Import them at the highest level
3. ???
4. Profit!

You could use babel-plugin-transform-runtime if you wanted, but a proper polyfill is still recommended, and if you don't like babel-polyfill you could always try alternatives like core-js. Sadly babel-preset-env cannot detect react-native and if they do so the polyfill cherrypicking process can be simplified and can reuse many builtins...

Proxy cannot be polyfilled by babel-polyfill, so do keep in mind that proxy-polyfill can be non-compliant, even if it is backed by Google.