The issue tracker for js2-mode illustrates that such a parsing approach is no guarantee of real-world accuracy either.<p><a href="https:&#x2F;&#x2F;github.com&#x2F;mooz&#x2F;js2-mode&#x2F;issues" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;mooz&#x2F;js2-mode&#x2F;issues</a><p>The goal just shifts from having a semi-accurate regexp tokenizer, to having the language mode&#x27;s complex parser match the complex parser of the language it targets—which will pretty much never happen, unless the language is exquisitely simple, like maybe restricted dialects of Scheme... or Brainfuck.