BEGIN {
   my %escapes = (
      "\\" => "\\\\",
      "\"" => "\\\"",
      "\n" => "\\n",
      "\r" => "\\r",
      "\t" => "\\t",
   );

   my ($escapes) = map qr/[$_]/,
                   join '',
                   map quotemeta,
                   keys %escapes;

   sub to_js_str_literal {
      for (my $s = $_[0]) {
         s/($escapes)/$escapes{$1}/g;
         s/([^\x20-\x7E])/sprintf("\\u%04X", ord($1))/eg;
         return qq{"$_"};
      }
   }
}