Express 4.x, socket.io, formidable文件的上传（进度条）、下载

var express = require('express');
var path = require('path');
var app = express();
var port = 8888;
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
// include static files
app.use(express.static(path.join(__dirname, 'public')));
// upload destination setup
app.set('files', path.join(__dirname, '/public/files'));
var index = require('./routes/index');
// router
app.get('/upload', index.list);
app.post('/upload', index.submit(app.get('files')));
app.get('/file/:id/download', index.download(app.get('files')));
var server = app.listen(port);
console.log("Listening on port: " + port);
var io = require('socket.io')(server);
app.set('socketio', io); // store a reference to the io object, can be passed to routes

var formidable = require('formidable');
var fs = require('fs');
var path = require('path');
var fileUploaded = new Map(); // store uploaded files
exports.list = function (req, res) {
  res.render('index', {
    title: "File upload",
    fileUploaded: fileUploaded
  });
};
• Router - Submit and Upload: index.js
javascript
exports.submit = function (dir) {
  return function (req, res, next) {
    var form = new formidable.IncomingForm();
    // high level formidable API
    form.uploadDir = dir; // set destination
    form.hash = 'md5'; // use hash algorithm, we can get hash value by 'file.hash'
    form.parse(req, function (err, fields, files) {
      // console.log(fields);
      // console.log(files);
      files.file.lastModifiedDate = files.file.lastModifiedDate.toLocaleString();
      var f = {
        newName: fields.name.length == 0
          ? files.file.name
          : fields.name + path.extname(files.file.name),
        file: files.file
      };
      if (fileUploaded.has(files.file.hash)) {
        form.emit('aborted'); // doesn't work!?
        console.log('aborted');
      } else {
        fileUploaded.set(files.file.hash, f); // add to map
      }
      fs.rename(files.file.path, path.join(form.uploadDir, files.file.name), function (err) {
        if (err) {
          console.log(err);
        }
        res.redirect('/upload');
        console.log('Finished.');
      });
    });
    var io = req.app.get('socketio'); // get reference to socket.io
    // listening progress event and send data to client
    form.on('progress', function (bytesReceived, bytesExpected) {
      var percent = Math.floor(bytesReceived / bytesExpected * 100);
      console.log(percent);
      var progress = {
        name: 'progress',
        percent: percent
      };
      // emit event : progress
      io.emit('progress', progress); //notify all client, no session here
    });
  }
};

exports.download = function (dir) {
  return function (req, res, next) {
    var id = req.params.id;
    var file = fileUploaded.get(id);
    var targetPath = path.join(dir, file.file.name);
    // second parameter can be used to specify file name
    res.download(targetPath, file.newName);
  };
};

<table>
<caption>Uploaded Files</caption>
<thead>
<tr>
  <th>Name</th>
  <th>Size</th>
  <th>Type</th>
  <th>DateTime</th>
  <!--<th>Details</th>-->
</tr>
</thead>
<tbody>
<% fileUploaded.forEach(function(item, key, mapObj) { %>
<tr>
  <td><a href='/file/<%=key%>/download'><%=item.newName%></a></td>
  <td><%=item.file.size%></td>
  <td><%=item.file.type%></td>
  <td><%=item.file.lastModifiedDate%></td>
  <!--lastModifiedDate, mtime???-->
  <!--<td><%=JSON.stringify(item.file)%></td>-->
</tr>
<%})%>
</tbody>
</table>

// client validation
function validateInput() {
  var uploadButton = document.forms[0].upload;
  uploadButton.onclick = function () {
    var file = document.forms[0].file.value;
    if (file.length == 0) {
      document.getElementById('uploadProgress').innerText = 'No file selectd!';
      return false;
    }
    var name = document.forms[0].name.value;
    if (name.length != 0) {
      var invalidChars = name.match(/[^a-zA-Z0-9_()\u4e00-\u9fa5]+/g); // match invalid file name
      if (invalidChars.length != 0) {
        document.getElementById('uploadProgress').innerText = 'Invalid file name!';
        return false;
      }
    }
  }
}
// communication between client and server using socket.io
function getUploadProgressFromServer() {
  var socket = io.connect("http://localhost:8888");
  var uploadProgress = document.getElementById("uploadProgress");
  var bar = document.getElementById('bar');
  socket.on("progress", function (data) {
    if ("progress" === data.name) {
      uploadProgress.innerText = data.percent + '%';
      bar.style.width = data.percent / 100 * document.body.offsetWidth + 'px';
    } else {
      console.log("There is nothing.", data);
    }
  });
}

{"size":102056,
"path":"D:\\...\\uploadProgress\\public\\files\\upload_0dcfbb98abc3b2c7356f87f218df715b",
"name":"debug.log",
"type":"application/octet-stream",
"mtime":"2017-04-26 20:58:08",
"hash":"40f2f78bff67c9e6164aa790f9627d83"}