express - How to check & confirm if dropzone is actually sending file to server -

i using dropzonejs , using following code initialize dropzone:

var mydropzone = new dropzone("div#myid", { url: "/file/post"}); 

on server side, using expressjs\nodejs & using following code:

fs.readfile(req.files.displayimage.path, function (err, data) {   // ...   var newpath = __dirname + "/uploads/uploadedfilename";   fs.writefile(newpath, data, function (err) {     res.redirect("back");   }); }); 

problem req.files coming undefined.

i want know when upload file, there way through developertoolbar check payload & confirm whether file been sent or not?