use nodejs middleware to seperate SEO source

gistfile1.js

app.use(function(req, res, next) {
  
  var frag = req.query._escaped_fragment_;

  if (!frag) return next();

  if (frag){
    //處理指向的對應route
  }
  
  try {
    var file = __dirname + "/snapshots" + frag;
    res.sendfile(file);
  } catch (err) {
    res.send(404);
  }
  
});