[no-unreachable] switch statement

When break is used consistently to avoid programmer errors in the future, eslint will warn about having return & break (the break being unreachable).

I think this is similar to the (redundant) trailing commas where they are preventing future errors so this should be allowed:

switch (cond) {
  case 'one':
    if (cond1) 
      return 'denied';
    else 
      return 'good'
  break; // <--- this will trigger the warning of unreachable code
  case 'two':
    simple code..
    just statements..
  break;
  default: 
    return 'unexpected';
}

(note: it may also be a stylistic/formatting preference that all cases have break pairs)

[gblazex]

This may work as you guys intended, but then your intentions simply don’t cover all the cases. 😃 As with other rules it’s not always an on/off binary option, sometimes you need more options to have a reasonable setup.

Disabling globally or even around a switch is not a solution.

Consider the following example:

switch (cond) {
  case 'one':
    if (cond1) 
      return 'denied';
    else 
      return 'good'
  break; // <-- doesn't make sense to force you to remove this line
  case 'two':
    if (cond1) 
      return 'denied';
    else 
      return 'good'
    leftAfterRefactor(); // <-- but this is a valid place where it should warn you
  break;
}

In the first case it makes no sense for ESLint to enforce the rule, but if you turn it off you lose the helpful warnings e.g. in the second case.

[HarryPehkonen]

This is the solution that I use, and my story of the whole issue. I’m using eslint v.2.9.0.

For what it’s worth, if I don’t see “break” at the end of every switch/case, I get concerned. From my C-days, I am used to adding /* NOTREACHABLE */ or /* FALLTHROUGH */ inside switch/case if I’m intending something specific. Having support for something like this (“case” by “case”) seems beneficial.

Specifying:

switch (x) {
case "something":
    /* eslint no-unreachable: 0 */
    return x;
    break;
    /* eslint no-unreachable: 2 */

… doesn’t help because it’s the final rule that applies to the whole .js file (the first no-unreachable is, in effect, ignored). This is, of course, by design.

Adding either eslint-disable-line or eslint-disable-next-line inside /* */ comments:

return;
/* eslint-disable-line no-unreachable */
/* eslint-disable-line no-unreachable */ break; /* eslint-disable-line no-unreachable */
/* eslint-disable-line no-unreachable */

…doesn’t help either (yes, I tried all four possible places for it).

These, however, work (the use of // instead of /* */ for the comments is required – is that a bug?):

return;
/* eslint-disable no-unreachable */
break;
/* eslint-enable no-unreachable */

return;
// eslint-disable-next-line no-unreachable
break;

return;
break; // eslint-disable-line no-unreachable

I hope that helps.

Harry.