My current method is this:

var request = require('request');

var mime = require('mime');

var fs = require('fs');

var uri = 'http://www.sweetslyrics.com/images/img_gal/25646_christina-perri-213968.jpg';

request({

        'method':'GET',

        'uri': uri

},function(err, response,body){

    var tmp_path = '/tmp/123456';

    fs.writeFile(tmp_path, body, function(err) {

        console.log(mime.lookup(tmp_path));  //application/octet-stream ?????

    });

});

The image is obviously a picture, but node-mime says it's application/octet-stream. Why?

Note:
- I do not want to rely on the Response Headers content-type, because based on my experience, sometimes those response headers are set incorrectly...and they do not determine the true file type. (that's why I save it to a file, and then have node-mime determine it for me!)

I want to know the best way to determine if a file is an image, with 0 margin of error.

Edit: I just realized that node-mime isn't magic. It just checks for the extension :( ...

Edit2: I found this: https://github.com/SaltwaterC/mime-magic