`valid-typeof` does not report invalid comparisons to `undefined`

What version of ESLint are you using? 3.1.0

What parser (default, Babel-ESLint, etc.) are you using? default

Please show your full configuration:

{
  "rules": {
    "valid-typeof": 2
  }
}

What did you do? Please include the actual source code causing the issue.

// oops, this was probably supposed to be the string 'undefined'
if (typeof window === undefined) {
  foo();
}

What did you expect to happen?

I expect ESLint to report an error, since the global undefined value is not a valid typeof comparison.

What actually happened? Please include the actual, raw output from ESLint.

ESLint did not detect any errors.

[nzakas]

I think the only way we can possibly do something that makes sense is to add an option like requireStringLiterals that ensures the RHS is always a string. Anything else is just guessing and not appropriate for this rule.

[ilyavolodin]

Sorry, I meant string literals.