Debug JS Remotely

[sm2017]

Is this a bug report?

(Yes , 100000000%)

Have you read the Contributing Guidelines?

(Yes)

Environment

1. react-native -v:

react-native-cli: 2.0.1
react-native: 0.47.1

2. node -v:

v8.1.3

3. npm -v:

5.0.3

4. yarn --version:

0.27.5

Then, specify:

• Target Platform: Android

• Development Operating System: Windows10

• Build tools: react-native run-android

Steps to Reproduce

You cannot easily reproduce error , this is a random cryptic error

Expected Behavior

Executing JS code must not depends on remote debug , So works well when remote debug is off or on

Actual Behavior

For android when remote debug is ON , code works and when OFF not works

Foe more information see:

https://medium.com/@jordan_mohi/cant-find-variable-symbol-in-react-native-782489d86bd7
#15786
#15497

Reproducible Demo

(N/A)

[iegik]

I think, it's not a bug, it is a feature.
With Debug enabled, I think for debug needs are included some additional es6 modules, such as Request, Symbol or some of RegExp features, So, ensure, that You have all dependences included, before start to scripting.

For example,

npm install --save es6-symbol
import 'es6-symbol/implement';

In production mode, you would not need to have redundant script included.

Also, try the following configuration in gradle:

buildTypes {
        debug {
            shrinkResources true
            debuggable true
            minifyEnabled true
            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro", "devsupport.pro"
            applicationIdSuffix ".debug"
        }
        release {
            shrinkResources true
            signingConfig signingConfigs.release
            minifyEnabled true
            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
        }
    }

• Trouble handling android hardware back button react-navigation/react-navigation#1819

[sm2017]

@iegik I think it is a bug because , I use Symbol in a js file from 6 months ago , I don't change this file from 2-3 months ago , suddenly react-native Can’t find variable: Symbol only on android when remote debug is not enabled (see #15786). If it is not a bug and a feature why iOS has not this feature?

If you think it is a feature , Why we lost BackHandler on android when remote debug is off? (See #15497)

[iegik]

@sm2017 You can also try to debug with Android Monitor or logcat

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. If you think this issue should definitely remain open, please let us know why. Thank you for your contributions.

[dummerbd]

Just fyi for people finding this issue via Google, the problem as I understand it is Symbol is not supported in the current version of the JavaScript Core shipped with Android but it is supported natively on iOS which has a newer version of JSC. The reason you don't see this issue when using Remote Debug is because your JavaScript actually runs remotely in Chrome which does support Symbol.

Long story short, use a polyfill for now like es6-symbol.

[joeytwiddle]

A possible polyfill solution is mentioned here