>Like, extending from a Module object?
No, it’s more when I derive from an imported class. I had a “ReceivePort”
module and a “SendPort” module that both use a base class “CommPort”. Since a
module “seems to be” an isolated scope I thought I could extend CommPort
individually inside each module. I knew the browser cached the download, but
didn’t know about it caching a ”live” object.
This isn’t exactly what I was doing, but it close to the idea.
```
Module: CommPort
class CommPort {
set duplexHost(host) { … }
}
// Module: ReceivePort
import { CommPort } from…
class ReceivePort extends CommPort { }
// Module: SendPort
import { CommPort } from…
class SendPort extends CommPort { }
// Module: DuplexPort
import { SendPort } from…
import { ReceivePort } from…
class DuplexPort {
#sendPort = new SendPort();
#receivePort = new ReceivePort();
constructor(){
sendPort.duplexHost = this;
receivePort.duplexHost = this;
}
}
```
I have “Worker Farms” where each worker has multiple `DuplexPort` to
communicate with other workers. I would send a message to one worker and
pretty much all of them received the message. The problem wasn’t obvious to me,
especially since I was generally new to ES at the time.
What happens is the browser downloads `CommPort` once, and also creates a
single `CommPort` object. All of the scoped `CommPort` objects are just
pointers to that. So the imported `CommPort` in `SendPort` is the same
`CommPort` as the one in `ReceivePort`. When the `DuplexPort` registers itself
on the ports (even though it seems isolated within a module scope) the
registration “leaks” up to the live ghosted `CommPort`. Every message was going
through the last port registered! This is one reason for the approach I’m
taking. When I `inject` I get a “clean” base class to inherit from.
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