javascript实现上传控件预览及文件保存路径

javascript实现上传控件预览及文件保存路径
前端代码
上传附件：  <asp:FileUpload ID="FileUploadControl" runat="server" />
           <asp:RequiredFieldValidator ID="fjyz" runat="server"  ControlToValidate="FileUploadControl"  ErrorMessage="附件不能为空"  ForeColor="red">*</asp:RequiredFieldValidator>
           <label id="fsc" runat="server"></label>
<br />
      附件预览：<br />  <img id="imagePreview" src="#" alt="Image preview" style="display: none;" />
           <script>document.getElementById('FileUploadControl').addEventListener('change', function (event) {
                   var file = event.target.files[0];
                   var reader = new FileReader();
                   reader.onload = function (e) {
                       document.getElementById('imagePreview').src = e.target.result;
                       document.getElementById('imagePreview').style.display = 'inline';
                   };
                   reader.readAsDataURL(file);
               });</script>




后端代码
protected void UploadButton_Click(object sender, EventArgs e)
    {
        

        zt = this.ydlx.Text;
       
       

        if (FileUploadControl.HasFile)
        {
            try
            {
                string filename = pic + "-" + Path.GetFileName(FileUploadControl.FileName);
                FileUploadControl.SaveAs(Server.MapPath("~//upload/") + filename);
                StatusLabel.Text = "上传状态: 文件上传成功!'" + eBase.getAbsolutePath() + "http://115.159.193.242//upload/" + filename;
                fj = eBase.getAbsolutePath() + "http://115.159.193.242//upload/" + filename;





            }
            catch (Exception ex)
            {
                StatusLabel.Text = "上传状态: 文件无法被上传. 原因: " + ex.Message;
            }
           



        }
      
    }