I am a little new to javascript. I have got one javascript function which is generating xlsx file from HTML table. It's working fine but as soon as the file gets generated, it's downloading the file instead I am looking to save it on my server. The function is like below

function ExportToExcel(type, fn, dl) {
       var elt = document.getElementById('tour');
       var wb = XLSX.utils.table_to_book(elt, { sheet: "sheet1" });
       return dl ?
         XLSX.write(wb, { bookType: type, bookSST: true, type: 'base64' }):
         XLSX.writeFile(wb, fn || ('MySheetName.' + (type || 'xlsx')));
}

and I am calling it like below:

onclick="ExportToExcel('xlsx')"

How to store the file instead of downloading it?