FileUpload实现上传预览功能

<asp:FileUpload ID="FileUpload1" runat="server" onchange="chgImg(this)" />
 <div>
                            <img src="" id="Photo" runat="server" style="max-height: 80px;float:left" />
                            <div id="preview"></div>
                        </div>

   function chgImg(file) {
            //img控件预览图片
            //var FileUpload1 = $("#FileUpload1").val();
            //div预览图片（兼容模式）
            $("#ContentPlaceHolder1_Photo").attr("src", "");
            var prevDiv = document.getElementById('preview');
            if (file.files && file.files[0]) {
                var reader = new FileReader();
                reader.onload = function (evt) {
                  
                    prevDiv.innerHTML = '<img src="' + evt.target.result + '" style="max-height:80px;" />';
                }
                reader.readAsDataURL(file.files[0]);
            }
            else {
                prevDiv.innerHTML = '<div class="img" style="max-height:80px;filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src=\'' + file.value + '\')"></div>';
            }
        }