var imgB64Arr = [];
//fileInput是input标签
fileInput.change=function(){
  var files = this.files;
  for(var j = 0; j < files.length; j++){
    var reader = new FileReader();
    reader.readAsDataURL(files[j]);
    reader.onload = function(){
      var v64 = this.result;
      imgB64Arr.push(b64);
      //...预览显示逻辑...
    };
  }
};

  var uploadingImg = false; //标示当前是否有正在上传的东西
  setInterval(function(){
    if(!uploadingImg && imgB64Arr.length > 0){
      var nowUp = imgB64Arr[0];
      uploadingImg = true;
      var imgName = 'xxx';//文件命名策略
      subimtInageFile(imgName, imgBa64s[nowUp.img], function(retu, err){
        if(err){
          //TODO: 错误处理
          return;
        }
        //上传完成相关数据维护
        imgB64Arr = imgB64Arr.length > 0 ? imgB64Arr.slice(1) : [];
        uploadingImg = false;
        //TODO: 显示更新逻辑
      });
    }
  }, 300);
  function subimtInageFile(imgName, ba64, callback){
    var formData = new FormData();
    formData.append('up_photo', convertBase64UrlToBlon(ba64));
    //这里服务端要留意：没找到怎么把名字写到上传文件里，所以将文件名直接作为单独一个post参数提交
    formData.append('file_name', imgName); 
    $.ajax({
      url: '...',
      type: 'POST',
      data: formData,
      dataType: 'json',
      processData: false, //否则jquery会报错
      contentType: false,
      success: function(sd){
        callback && callback(sd);
      },
      error: function(xhr, err){
        callback && callback(false, err);
      }
    });
  }
  //图片处理，base64欢迎成图片blob
  function convertBase64UrlToBlon(base64Str){
    var bs = window.atob(base64Str.split(',')[1]);
    var ab = new ArrayBuffer(bs.length);
    var ia = new Uint8Array(ab);
    for(var i = 0; i < bs.length; i++) ia[i] = bs.charCodeAt(i);
    var bb = new Blob([ab], {type: 'image/png'});
    return bb;
  }