JavaScript 图片预览效果 http://www.iteye.com/topic/554752
预加载图片
http://justcoding.iteye.com/blog/695929
mg.readyState!= complete 权限问题 也是一个无用题
http://wangjc-opal.iteye.com/blog/766043
简便无刷新文件上传系统
http://www.cnblogs.com/cloudgamer/archive/2009/12/01/Quick_Upload.html
JavaScript 图片上传预览效果
http://www.cnblogs.com/cloudgamer/archive/2009/12/22/ImagePreview.html