E0346: using '==' against a regular expression literal always returns 'false'

In JavaScript, writing /regularexpression/ creates a new RegExp object. so comparing a regular expression literal using ==, ===, !=, or !== will always give the same result (false or true):

function isCapitalized(s) {
  return /^[A-Z]/ == s;
}

To fix this issue, if you intended to check if a string matches a regular expression, call the RegExp#test method instead of writing ==:

function isCapitalized(s) {
  return /^[A-Z]/.test(s);
}

Introduced in quick-lint-js version 2.10.0.

Documentation for other errors