使用multiparty做文件上传时，解析不了

app.js

app.get('/upload',upload.getPostFile);
app.post('/upload',upload.postFile);

upload.ejs

<form action="" enctype="multipart/form-data" method="post">
    <input type="text" name="title"><br>
    <input type="file" name="upload" multiple="multiple"><br>
    <input type="submit" value="Upload">
</form>

upload.js

var multiparty = require('multiparty');
var util = require('util');

exports.getPostFile = function(req, res){
   res.render('upload',{ title:"上传"});
};
exports.postFile = function(req,res){
   var form = new multiparty.Form(); 
   form.parse(req, function(err, fields, files) {
      res.writeHead(200, {'content-type': 'text/plain'});
      res.write('received upload:\n\n');
      res.end(util.inspect({fields: fields, files: files}));
    });
};

当我去到upload这个页面的时候，点击上传，一直在Loading状态。不知道哪里写错了，好像没有解析post的文件。