title: If comments are safe, then why doesn't `x = 0; x+/*cmt*/+;` or `var f/*cmt*/oo = 'foo';` work?
body: <p><a href="https://stackoverflow.com/questions/12659020/are-comments-100-safe-on-all-the-major-environments/12659032#comment17078409_12659032">This</a> thread inspired the question.  Here are the code samples again.  I'm looking for an answer that tells exactly what is going on.</p>
  
  <p>Both <code>x = 0; x+/*cmt*/+;</code> and <code>var f/*cmt*/oo = 'foo';</code>  produce syntax errors, which renders the answers in <a href="https://stackoverflow.com/q/12659020/1597180">this</a> question wrong.</p>