Node.js 使用文件-Delivery.js和socket.io发送参数

我正在尝试使用nodejs、socket.io和delivery.js上传一个文件。文件上传对我来说很好，但我需要随文件发送一些参数。但我不知道如何才能做到这一点！这是到目前为止我的代码

Client.html

var socket = io.connect();

  var delivery = new Delivery(socket);

  function sendFile(){

    delivery.on('delivery.connect',function(delivery){

        var file = document.getElementById("file").files[0];
        var extraParams = {foo: 'bar'};
        delivery.send(file, extraParams); //trying to send the params with file
        return false;
    });

    delivery.on('send.success',function(fileUID){
      alert("file was successfully sent.");
    });

  }

还有我的server.js

io.sockets.on('connection', function(socket){
  var delivery = dl.listen(socket);
  delivery.on('receive.success',function(file){
  // delivery.on('receive.success',function(file,params){<--tried this also

    var params = file.params;
    console.log(params);
    fs.writeFile(file.name,file.buffer, function(err){
      if(err){
        console.log('File could not be saved.');
      }else{
        console.log('File saved.');
      };
    });
  });
});

io.sockets.on（'connection'，函数（socket）{
var delivery=dl.listen（套接字）；
delivery.on（'receive.success'，函数（文件）{
//delivery.on（'receive.success'，函数（文件，参数）{