The guideline is, if the entire construct can fit on one line, it should be on one line; if not, each item should be on its own line.

In other words, for any of { … }, ( … ), [ … ].

Actually, after rereading the ESLint documentation, it looks like I misunderstood the allowAllPropertiesOnSameLine option. I didn't realize setting it to false would also mark the line as incorrect if the properties were on the same line as the curly braces.

So it looks like ESLint doesn't have the configuration available to make the following happen:

// correct
const obj = { foo: "foo", bar: "bar", baz: "baz" };

// correct
const obj2 = {
    foo: "foo",
    bar: "bar",
    baz: "baz"
};

// incorrect, but ESLint allows it with `allowAllPropertiesOnSameLine` set to true
const obj3 = {
    foo: "foo", bar: "bar", baz: "baz"
};

According to what I thought the Airbnb style guide promoted (and what I believe you're confirming) is that obj3 is incorrect, since it spans three lines (multiline), but does not place each item on its own line?

But unfortunately we can't currently force the error to be picked up by ESLint (not without having obj1 become a false positive).

Is there not a different rule that complains about that one? If not, then we should propose one to eslint :-)

It looks like array-element-newline needs a new ESLint rule as well (to handle the same exact case for arrays). And then on the same topic of multiline, this issue applies as well, requiring another ESLint rule.

I'll go ahead and submit feature requests for all of the above when I have the time to work on the pull request for the implementation of those rules.

you mean feature request like this?
eslint/eslint#11620