es6-symbol | ECMAScript 6 Symbol polyfill | Script Programming library

I'm trying to understand the difference between Symbol() and Symbol.for() in regard to cross realm.

I have read this article:http://2ality.com/2014/12/es6-symbols.html where it is said that:

Symbols have individual identities and thus don’t travel across realms as smoothly as other primitive values. That is a problem for symbols such as Symbol.iterator that should work across realms: If an object is iterable in one realm, it should be iterable in others, too. If a cross-realm symbol is provided by the JavaScript engine, the engine can make sure that the same value is used in each realm. For libraries, however, we need extra support, which comes in the form of the global symbol registry: This registry is global to all realms and maps strings to symbols. For each symbol, libraries need to come up with a string that is as unique as possible. To create the symbol, they don’t use Symbol(), they ask the registry for the symbol that the string is mapped to. If the registry already has an entry for the string, the associated symbol is returned. Otherwise, entry and symbol are created first.

Frankly, I don't know what does it mean that a symbol is accessable in one realm and not accessable in other. I have tried this piece of code:

The ERROR I see is this:

I SAW A LOT OF QUESTIONS REGARDING THIS ERROR BUT ALL WERE OF SOME DIFFERENT CONTEXT. I see that this error has to be something relating to name collisions in node_modules. NOT DUPLICATE

MetroBundler in terminal:

The RN android app is not loading after the splash screen in the release build. While in the debug mode, it works fine.

Here is ADB LOG FILE from 08-20 00:16:55 (App is opened) to 08-20 00:17:17. There isn't any error here that can actually cause the app to hang.

Please suggest how to go ahead and solve this issue. Really frustrating.

package.json

I'm struggling with my React Native app... It used to be deployed correctly with no errors before I updated many of the librairies I used in react-native, but now I have errors on Android & iOS.

It works fine with react-native run-android or with Android Studio, but my release APK does not pass Google Play tests.

Here is the Google Play logcat of the errors (partially) :

12-12 01:26:15.554: E/ReactNativeJS(13327): undefined is not an object (evaluating 'e.length') 12-12 01:26:15.556: I/Dpps(892): int DppsFeatureAd3::AdCalcCalibParams(struct DppsAdCfgParam &)():445 calib_a 14, calib_c 0, calib_d 0 12-12 01:26:15.558: E/ReactNativeJS(13327): Module AppRegistry is not a registered callable module (calling runApplication) 12-12 01:26:15.563: E/NetworkScheduler(11214): ignoring stale queue check message 12-12 01:26:15.563: E/NetworkScheduler(11214): --------- beginning of crash 12-12 01:26:15.564: E/AndroidRuntime(13327): FATAL EXCEPTION: mqt_native_modules 12-12 01:26:15.564: E/AndroidRuntime(13327): Process: com.mdef.mymatchup, PID: 13327

And here is my package.json :

I'm trying to build my ionic app with --prod flag but I'm getting issues doing it.

After upgrading to ionic 3.18, some time ago, there was some problems and I couldn't run my app anymore. I forgot what were the problems but I solved them somehow with some tweakings in my package.json, if I remember well, and I was able to run the app.
But since that, I can't get it to build with --prod flag (but it works fine without).

Today I was looking into this problem and tried deleting my node_modules and rebuilding it following this advice. It solved the specific issue there was, but I still cannot build the app.

Here is the result of rebuilding node_modules folder running npm i: (I removed a few lines without any error in the middle, because it was too long to post otherwise.)

When using a ES6 Symbol as the key for a key/value pair in LocalStorage, can we then still access it after reloading the page?

I found this tutorial that claims this to be possible when using Symbol.for, but so far I have no success and get an undefined when I try to retrieve the LocalStorage key/value pair.

As a side question: does it make sense to use Symbols over here?

I am working on a home automation project in NodeJS with several modules. These modules need access to data devices within a central DeviceManager. Normally I would create a singleton for this purpose so all modules access the same state of the DeviceManager.

To create a singleton I use:

I am learning Es6: Symbols. I am playing with it and trying to create a symbol using another symbol as description: