Export html table to excel using javascript

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C#

ASP.NET

Javascript

Hi All ,
I want to export html table to excel using JavaScript and i am done .
But when i am exporting it is directly showing to excel page, actually i want it to first it should show a dialog box with "Open","Save" and "Cancel" option . But i am not able to find the solution . please help me out for this .
JavaScript code is given below :

function write_to_excel() {
    str = "";
    var mytable = document.getElementById("tbExport");
    var rowCount = mytable.rows.length;
    var colCount = mytable.getElementsByTagName("tr")[0].getElementsByTagName("th").length;
    var ExcelApp = new ActiveXObject("Excel.Application");
    var ExcelSheet = new ActiveXObject("Excel.Sheet");
    //ExcelSheet.Application.Visible = true;
    for (var i = 0; i < rowCount; i++) {
        for (var j = 0; j < colCount; j++) {
            if (i == 0) {
                str = mytable.getElementsByTagName("tr")[i].getElementsByTagName("th")[j].innerText;
            }
            else {
                str = mytable.getElementsByTagName("tr")[i].getElementsByTagName("td")[j].innerText;
            }
            ExcelSheet.ActiveSheet.Cells(i + 1, j + 1).Value = str;
        }
    }
    ExcelSheet.autofit;
    ExcelSheet.Application.Visible = true;
    DisplayAlerts = true;
    CollectGarbage();
}

Thanks & Regards