Download Excel from Ajax call in ASP.NET

<asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server">
 
 <input type="button" onclick="exported()" value="Export"/>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js" type="text/javascript"></script>
<script>
 
    function exported(e) {
        $.ajax({
            type: "POST",
            url: '/api/AjaxAPI/ExportExcel', //call your controller and action
            contentType: "application/json; charset=utf-8",
            dataType: "json",
        }).done(function () {
                //use window.location.href for redirect to download action for download the file
                window.location.href = '/api/AjaxAPI/Download';
        });
    }
    </script>
 
</asp:Content>

using Syncfusion.XlsIO;

Imports Syncfusion.XlsIO

[HttpPost]
// POST api/<controller>
public void ExportExcel()
{
   //save the file to server temp folder
   string fullPath = Path.Combine(HostingEnvironment.MapPath("~") + FileName);
            
   using (ExcelEngine excelEngine = new ExcelEngine())
   {
      IApplication application = excelEngine.Excel;
 
      //Create a workbook with a worksheet
      IWorkbook workbook = application.Workbooks.Create(1);
 
      //Insert sample text into cell “A1”
      workbook.Worksheets[0]["A1"].Text = "Hello World";
 
      workbook.Version = ExcelVersion.Excel2016;
 
      //Save the workbook 
      workbook.SaveAs(fullPath);
   }
}
[HttpGet]
public HttpResponseMessage Download()
{
   //get the temp folder and file path in server
   string fullPath = Path.Combine(HostingEnvironment.MapPath("~") + FileName);
   byte[] fileByteArray = System.IO.File.ReadAllBytes(fullPath);
   System.IO.File.Delete(fullPath);
   var stream = new MemoryStream(fileByteArray);
   var content = new HttpResponseMessage(HttpStatusCode.OK)
   {
      Content = new StreamContent(stream)
   };
   content.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");            
   return content;
}

<HttpPost>
Public Sub ExportExcel()
'save the file to server temp folder
   Dim fullPath As String = Path.Combine(HostingEnvironment.MapPath("~") & fileName)
 
   Using excelEngine As ExcelEngine = New ExcelEngine()
      Dim application As IApplication = excelEngine.Excel
 
      'Create a workbook with a worksheet
      Dim workbook As IWorkbook = application.Workbooks.Create(1)
 
      'Insert sample text into cell “A1”
      workbook.Worksheets(0)("A1").Text = "Hello World"
      workbook.Version = ExcelVersion.Excel2016
 
      'Save the workbook
      workbook.SaveAs(fullPath)
   End Using 
End Sub
<HttpGet>
Public Function Download() As HttpResponseMessage
   Dim fullPath As String = Path.Combine(HostingEnvironment.MapPath("~") & FileName)
   Dim fileByteArray As Byte() = System.IO.File.ReadAllBytes(fullPath)
        System.IO.File.Delete(fullPath)
   Dim stream = New MemoryStream(fileByteArray)
   Dim content = New HttpResponseMessage(HttpStatusCode.OK) With {
            .Content = New StreamContent(stream)
   }
   content.Content.Headers.ContentType = New MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
   Return content
End Function