busboy-connect fires on finish before the end of save file (node.js , express)

Question

I use busboy connect to get the upload data from my client. I try to save the data and then on.finish to return status ok to the server. The problem is that the on.finish fires before the end of the file saving. Have I done something wrong or that's the way the module works?

server-side code :

        console.log("upload started dirname ", __dirname);
        var fstream;
        var result = [];
        var number_of_files = 1;
        req.pipe(req.busboy);
        req.busboy.on('field', function(fieldname, val) {
            field_obj = {}
            field_obj[fieldname] = val;
            result.push(field_obj);
            console.log(field_obj)
        });
        req.busboy.on('file', function(fieldname, file, filename) {
            console.log("Uploading: " + filename);
            //Path where image will be uploaded
            if (result.length > 0) {
                var file_type = filename.substr(filename.length - 4);
                filename = result[0].name + '_' + number_of_files + file_type;
                number_of_files++;
            }
            fstream = fs.createWriteStream(__dirname + "/" + filename);
            file.pipe(fstream);
            fstream.on('close', function() {
                console.log("Upload Finished of " + filename);
                result.push(filename);
                console.log("result ",result)
            });
        });
        req.busboy.on('finish', function() {
            console.log("form parsing finished")
            console.log("result finish",result)
            res.sendStatus(200)
        });

I would expect the "result finish" to be the last msg i see , but i get the following on my console:

Uploading: testSwf1.swf
Uploading: testSwf3.swf
form parsing finished
result finish [ { name: '123' }, { clickUrl: '234234' } ]
Upload Finished of 123_1.swf
result  [ { name: '123' }, { clickUrl: '234234' }, '123_1.swf' ]
Upload Finished of 123_2.swf
result  [ { name: '123' },
  { clickUrl: '234234' },
  '123_1.swf',
  '123_2.swf' ]

EDIT i also tried the on.end but that one didn't fired at all.

req.busboy.on('end', function() {
    console.log("DONE PARSING FORM")
    console.log("NEW result finish", result)
});

Answer 1

As mscdex suggested I used a variable to find when the writing is finised:

var fstream;
var result = [];
var number_of_files = 1;
var counter = 0; 
req.pipe(req.busboy);
req.busboy.on('field', function(fieldname, val) {
    field_obj = {}
    field_obj[fieldname] = val;
    result.push(field_obj);
    console.log(field_obj)
});
req.busboy.on('file', function(fieldname, file, filename) {
    counter++;
    console.log("Uploading: " + filename);
    //Path where image will be uploaded
    if (result.length > 0) {
        var file_type = filename.substr(filename.length - 4);
        filename = result[0].name + '_' + number_of_files + file_type;
        number_of_files++;
    }
    fstream = fs.createWriteStream(__dirname + "/" + filename);
    file.pipe(fstream);
    fstream.on('close', function() {
        counter--;
        console.log("Upload Finished of " + filename);
        result.push(filename);
        console.log("result ",result)
        if(counter == 0){
            console.log("writing finished");
            res.sendStatus(200);
        }
    });
});