Prepare for ES Modules

[AlCalzone]

Node 12.16+ supports the new EcmaScript modules and more and more packages are migrating. Currently all of them are also offering a CommonJS export, but that could change with time. At some point we will have to deal with that - meaning a migration of JS-Controller to ESM.

Helpful resources:

• https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
• https://www.sensedeep.com/blog/posts/2021/how-to-create-single-source-npm-module.html
• https://www.npmjs.com/package/esm - can be used to polyfill support easily
• https://nodejs.org/api/esm.html
• https://nodejs.org/api/packages.html

[Jey-Cee]

As there is actual no decision to do this now*, here are arguments:

Pro:

• we don't have to worry that we suddenly have to implement it if a large number of modules just provide ESM
• we do not lose functionality while CJS could still be used
• we have a lot of time for transition

Contra:

• a lot of work to do

• now means starting with planning and prepare as soon as possible

[foxriver76]

I think, now that we have everything running through a TS compile step, it would now be easy to provide ESM for the packages of this monorepo.

Not sure, if this should be a priority for next controller @AlCalzone @Apollon77 @GermanBluefox

https://www.sensedeep.com/blog/posts/2021/how-to-create-single-source-npm-module.html

[Apollon77]

In fact just building it will not bring us any step further. We need to find out how to make our adapter approach ESM compatible, what this means for adapter-core, how we handle compact mode :-) (and such - and I did not started with javascript adapter and esm deps gg) ... So yes if starting with this it makes sense to also build ESM :-) but I think this is just the beginning fo the story

[foxriver76]

I think internally it should be fine now. Compact mode is covered in #1667 and the general Adapter approach needs to be done in adapter-core. So could this be closed or anything in the context of this ticket open?

For adapter-core we have a start at ioBroker/adapter-core#576