I succeed uploading file using node.js and the formidable module yet, the file that got save on the disk is in some kind of a bad format ( bad encoding) e.g. if I upload an imag
The problem is the that files.upload is not the content of the file, it is an instance of the File class from node-formidable.
Look at:
https://github.com/felixge/node-formidable/blob/master/lib/file.js
Instead of trying to write the file to disk again, you can just access the path to uploaded file like this and use fs.rename() to move it where you want:
fs.rename(files.upload.path, 'yournewfilename', function (err) { throw err; });