Javascript: Add awareness for rules unsupported by ESLint

[alextes]

I had no clue there were so many Airbnb JavaScript style rules that are currently not covered by ESLint. How do you feel about appending some note that mentions their existence to the ESLint configs?

I imagine this would help push more JavaScript to follow the full set of guides in multiple ways.

• The devoted could read them (and spread them directly).
• It could encourage the development of ESLint plugins for the uncovered guides. Many of them seem relatively easy to cover even!
• It could inspire people to help all get all guides across to people in ways I haven't thought of

[ljharb]

The expectation is that most people discover the configs from the guide, and not the reverse - the guide lists which sections have eslint rules, and any section that lacks a rule certainly would be a welcome PR to eslint.

It is impossible to programmatically enforce every style rule, so the default assumption should be that an eslint config is simply the automatable subset of a style guide.

[alextes]

@ljharb I feel like things work the other way around because in my experience people get recommended 'ESLint', often 'with the Airbnb style guide.' The Airbnb style guide being the ESLint config, not the actual style guide. I realize without solid numbers it's hard to support either position.

so the default assumption should be that an eslint config is simply the automatable subset of a style guide.

Precisely what I missed. I thought the justification for the rules in the configs was all there was. I thought everything 'Airbnb on good style' was written in response to ESLint, and thus based on the available rules. Now I discover it is (more sensibly) written in response to JavaScript and all its rules. Regardless, I've never seen someone link one of the unsupported style guide rules and didn't know they exist but that might just be me.

If I can find the numbers to support my experience I'll re-open 😄.