Get status code in express middleware

You can override res.end event that is being called whenever response ends. You can get statusCode of response whenever response ends.

Hope it helps you

var end = res.end;

res.end  = function(chunk, encoding) {
     if(res.statusCode == 200){
         // cache file only if response status code is 200
         cacheFile(cacheFilePath, body);
     }

     res.end = end;
     res.end(chunk, encoding);
};

you can use res.statusCode to the get the status.