download by nodejs

download

app.get('/download', function (req, res) {
    var param = req.query['filename'];
    if (!param) { return  res.sendStatus(401);}
    var file = __dirname + '/public/' + req.query['filename'];
    if (!fs.existsSync(file)) {return  res.sendStatus(404);}
    var filename = path.basename(file);
    var mimetype = mime.lookup(file);

    res.setHeader('Content-disposition', 'attachment; filename=' + filename);
    res.setHeader('Content-type', mimetype);

    var filestream = fs.createReadStream(file);
    filestream.pipe(res);
});