移动手机中实现端文件上传的例子

var Upload = (function(win, upload) {

  upload.submit = function() {
    var self = this,
      form = document.getElementById('form'),
      formdata = new FormData(form),
      xhr = new XMLHttpRequest();

    // xhr.upload 在 iOS Safari、 大部分 Android 4.0+ 的自带浏览器、Chrome 都支持
    xhr.upload.addEventListener("progress", self.onProgress, false);
    xhr.addEventListener("load", self.onSuccess, false);
    xhr.addEventListener("error", self.onError, false);
    xhr.addEventListener("abort", self.onCancel, false);

    xhr.open('post', form.action, false);
    xhr.send(formdata);
  }

  // 可以在 onProgress 的时候处理进度条
  upload.onProgress = function(e) {
    if (e.lengthComputable) {
      var progress = Math.round(e.loaded * 100 / e.total) + '%';
      console.log('on progress: ', progress);
    }
  }

  upload.onError = function() {}
  upload.onCancel = function() {}

  // 上传完成
  upload.onSuccess = function() {}

  return upload;

})(window, window.Upload || {});
FormData，这是另一种针对 XHR2 设计的新数据类型。使用 FormData 能够很方便地实时以 JavaScript 创建 HTML

var fs = require('fs'),
  formidable = require('formidable');

app.post('/upload', function(req, res) {
  var form = new formidable.IncomingForm(),
    data;

  // formidable 属性设置可以参考 github 上说明
  form.uploadDir = './uploads';
  form.encoding = 'utf-8';
  form.keepExtensions = true;
  form.maxFieldsSize = 1024 * 1024 * 50; // 50MB

  form.parse(req, function(err, fields, files) {
    console.log('on parse');
    res.writeHead(200, {'content-type': 'text/plain'});
    data = files.fileToUpload;
    res.end(JSON.stringify(data));
  });

  // 我们可以在文件上传完成后移到放置文件的目标目录
  form.on('end', function() {
    fs.renameSync(data.path, './uploads/'+ data.name);
  });
});