function imageloadingdown() {
        var url = window.location.href;
        var hiddenIFrameId = 'hiddenDownloader';
        var iframe = document.getElementById(hiddenIFrameId);
        if (iframe === null) {
            iframe = document.createElement('iframe');
            iframe.id = hiddenIFrameId;
            iframe.style.display = 'none';
            document.body.appendChild(iframe);
        }
        iframe.src = url;
    }

<table>
   <tr data-report_id="5">
    <td>
        <input type="button" id="donwload"/>
        <iframe id="hiddenDownloader"/>
    <td>
</tr>
        </table>

Content-Type:'application/force-download'
Content-Disposition:'attachment; filename=the_filename'

System.Web.HttpContext.Current.Response.ContentType = "application/force-download;";
System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename="+ fileInfo.Name);