Turn on no-fallthrough rule

[JLHwung]

Q	A
License	MIT

Turn on the no-fallthrough ESLint rules, which is included in the eslint:recommended preset.

Related: #11089 (comment)

[nicolo-ribaudo]

I hate that prettier doesn't include this comment, since conceptually it's a control flow statement similar to break/continue.

[kaicataldo]

Classic ambiguous comment indentation 😆

[nicolo-ribaudo]

@kaicataldo The comment on line 57 is not enough. Could eslint/eslint#10608 be reopened? 🙏 😅

[kaicataldo]

I wonder if we should allow it to be either the first or last, but not the middle? I know it's unlikely, but I think it would be good to avoid something like this triggering it:

/* eslint no-fallthrough: ["error", { "commentPattern": "fall-through[\\s\\w]*not allowed" }] */

switch(foo) {
    case 1:
        doSomething();
        // We don't want to fall through here
        // because fall-through is not allowed,
        // oh look, a run on sentence.

    default:
        doSomething();
}

[nicolo-ribaudo]

Doesn't this code already have that problem?

/* eslint no-fallthrough: ["error", { "commentPattern": "fall-through[\\s\\w]*not allowed" }] */

switch(foo) {
    case 1:
        doSomething();
        // We don't want to fall through here because fall-through is not allowed.

    default:
        doSomething();
}

[kaicataldo]

Yeah, it would. Might just be me, but the grouped line comments seem more error prone. It probably is the same thing in practice, though.