(question) eslint rule / plugin for guideline 7.15

[shelbyspeegle]

is there an eslint rule or plugin that enforces 7.15?

[ljharb]

Indeed! comma-dangle handles the trailing comma, and function-paren-newline, i believe, handles the rest.

comma-dangle should be linked here already; however, I'm still not 100% sure about function-paren-newline :-)

[shelbyspeegle]

awesome! thanks @ljharb.

i can't seem to find the right options for function-paren-newline that adheres to the airbnb eslint guideline 7.15.

in particular, i can't get eslint to bug me about the 'bad' example below.

// bad
console.log(foo,
  bar,
  baz);

// good
console.log(
  foo,
  bar,
  baz,
);

[ljharb]

Maybe we need to file something upstream on eslint about it?

[raunofreiberg]

@shelbyspeegle I tried both rules out and I'm getting both errors, the bad example included.

"comma-dangle": "error",
"function-paren-newline": "error"

What have you tried so far?

[shelbyspeegle]

thanks @raunofreiberg, that gets me close, unfortunately it allows these scenarios:

// bad?
console.log(
  foo,
  bar, baz,
  yo,
);

// bad?
console.log(
  foo, bar, baz,
  yo,
);

i assumed that this should produce an eslint error, but an example isnt provided for this type of case.

i did see this in the guide language that could suggest that this should error.

with each item on a line by itself

[ljharb]

Yes, that should be an error. Either the entire invocation fits on one line, or each argument is on a line by itself.

[GusBuonv]

Doesn't the "multiline" option on function-paren-newline along with the current "comma-dangle" implement 7.15 correctly? If so, this line should be updated. Edit: I can open a PR, but I want to verify this is correct first. Also, I think it should be "multiline-arguments" not "multiline" so as to allow line breaks before and after argument lists with a single item.

[shelbyspeegle]

@GusBuonv That works great for me!

For this test file, eslint errors show:

... and eslint --fix now properly resolves that to:

Using your suggested rules in this simple eslintrc.js.

module.exports = {
  extends: ['airbnb'],
  rules: {
    'function-paren-newline': ['error', 'multiline'],
  },
};

Thanks @GusBuonv!

[ljharb]

Reading the rule docs, it does seem like multiline-arguments is the option that would most closely match the guide's intent.

It was changed from "multiline" to "consistent" in 2018. eslint itself added multiline-arguments in 2019, so it seems like "consistent" was better than "multiline", but "multiline-arguments" may be better still.

I'm hesitant to make this change, however, until it's at least been verified on airbnb's own code. I'll reach out to folks there and see how it goes.

[ljharb]

Given that this rule is disabled by eslint-config-prettier, Airbnb won't be affected, so I think this is a reasonable semver-minor change to make. @GusBuonv please make that PR :-)

[GusBuonv]

@ljharb Done! If the PR is merged, it may still be a good idea to keep this issue open or open a new one. I assume 7.15 is also supposed to apply to argument destructuring. If it is meant to apply in this case, it is still not properly enforced, and current core ESLint rules don't provide a way to achieve the desired behavior.