<div class="upload-container">

  <input type="file" name="fileToUpload" id="fileToUpload" class="fileupload" />

</div> 

.upload-container {

  background-image: url(../../images/rv/add.jpg);

  background-repeat: no-repeat;

  width: 180px;

  height: 200px;

  padding-bottom: 10px;

  display: inline-block;

  vertical-align: middle;

  .fileupload {

    opacity: 0;

    filter: alpha(opacity=0);

    width: 200px;

    height: 200px;

  }

} 

$('.fileupload').change(function(event) {

  /* Act on the event */

  if ($('.fileupload').val().length) {

    var fileName = $('.fileupload').val();

    var extension = fileName.substring(fileName.lastIndexOf('.'), fileName.length).toLowerCase();

    if (extension == ".jpg" || extension == ".png") {

        var data = new FormData();

        data.append('upload', $('#fileToUpload')[0].files[0]);

        $.ajax({

          url: 'apply/upload',

          type: 'POST',

          data: data,

          cache: false,

          contentType: false, //不可缺参数

          processData: false, //不可缺参数

          success: function(data) {

            console.log(data);

          },

          error: function() {

            console.log('error');

          }

        });

    } 

  }

}); 

npm install formidable@latest 

var cacheFolder = 'public/images/uploadcache/';<br>exports.upload = function(req, res) {

  var currentUser = req.session.user;

  var userDirPath =cacheFolder+ currentUser.id;

  if (!fs.existsSync(userDirPath)) {

    fs.mkdirSync(userDirPath);

  }

  var form = new formidable.IncomingForm(); //创建上传表单

  form.encoding = 'utf-8'; //设置编辑

  form.uploadDir = userDirPath; //设置上传目录

  form.keepExtensions = true; //保留后缀

  form.maxFieldsSize = 2 * 1024 * 1024; //文件大小

  form.type = true;

  var displayUrl;

  form.parse(req, function(err, fields, files) {

    if (err) {

      res.send(err);

      return;

    }

    var extName = ''; //后缀名

    switch (files.upload.type) {

      case 'image/pjpeg':

        extName = 'jpg';

        break;

      case 'image/jpeg':

        extName = 'jpg';

        break;

      case 'image/png':

        extName = 'png';

        break;

      case 'image/x-png':

        extName = 'png';

        break;

    }

    if (extName.length === 0) {

      res.send({

        code: 202,

        msg: '只支持png和jpg格式图片'

      });

      return;

    } else {

      var avatarName = '/' + Date.now() + '.' + extName;

      var newPath = form.uploadDir + avatarName;

      displayUrl = UPLOAD_FOLDER + currentUser.id + avatarName;

      fs.renameSync(files.upload.path, newPath); //重命名

      res.send({

        code: 200,

        msg: displayUrl

      });

    }

  });

}; 

fs.renameSync(files.upload.path, newPath); //重命名 

form.on('progress', function(bytesReceived, bytesExpected) {

});