网页图片上传预览

js代码:

        function imgYL() {
            var preview = document.querySelector('#imgPhoto');
            var file = document.querySelector('#FileUpload3').files[0];
            var reader = new FileReader();
            reader.onloadend = function () {
                preview.src = reader.result;
            }
            if (file) {
                reader.readAsDataURL(file);
            } else {
                preview.src = "";
            }
        }

html代码:

<asp:Image ID="imgPhoto" runat="server" Style="height: 100px; width: 100px;" onerror="javascript:this.src='/UploadFiles/Map/timg.jpg';" />
<asp:FileUpload ID="FileUpload3" runat="server" onchange="imgYL();" />