<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>‘; ???????????} ???????}FileUpload实现上传预览功能
原文地址：https://www.cnblogs.com/daimaozidejiamao/p/8458124.html