Build tooling: Singletons across bundles

[flashbackzoo]

We're currently assigning instances we wish to use as singletons to the ss namespace.
This is because singletons (exported by ES6 modules) only work within the context of a
single Browserify bundle.

For context this is what I mean by an ES6 singleton.

singleton.js

class Singleton {
  ...
}

const singleton = new Singleton();

export default singleton;

Let's assume the lib bundle exposes singleton so other bundles can require it, as an external, at runtime. If the framework bundle imports the external singleton dependency, then all modules in the framework bundle will have access the same copy of singleton if they import it.

Likewise if the custom bundle imports singleton as an external dependency, all modules in
custom will get the same copy of singleton.

This works as expected within the context of one bundle but does not work across bundles. The copy of singleton that framework gets is not the same copy of singleton that custom gets.

Possible solutions:

• Could be solved by RFC-9
• Alternatively look into SystemJS

[tractorcow]

@chillu do you understand this issue? I'd need to invest a bit more time before I could hope to address this. :)