    var blob = item.getAsFile();
                // console.log(blob)
                var reader = new FileReader();
                reader.onload = function (event) {
                    var base64 = event.target.result;
                    //ajax上传图片
                    layer.load(1);
                    $.ajax({
                        url:"{% url 'upload_doc_img' %}",
                        type:"post",
                        data:{base:base64},
                        success:function(ret){
 