Javascript export only checked checkbox rows to excel

i recently come across this problem and after searching i am not able to finding a satisfying answer. i bound to ask this question. And Hope for best answers.

i am using below function to export checked checkbox from table but it exports the entire html table.

   function fnExcelReport()
    {
        var tab_text = '<table border="1px" style="font-size:20px" ">';
        var textRange; 
        var j = 0;
        var tab = document.getElementById('DataTableId'); // id of table
        var lines = tab.rows.length;

        // the first headline of the table
        if (lines > 0) {
            tab_text = tab_text + '<tr bgcolor="#DFDFDF">' + tab.rows[0].innerHTML + '</tr>';
        }

        // table data lines, loop starting from 1
        for (j = 1 ; j < lines; j++) {     
            tab_text = tab_text + "<tr>" + tab.rows[j].innerHTML + "</tr>";
        }

        tab_text = tab_text + "</table>";
        tab_text = tab_text.replace(/<A[^>]*>|<\/A>/g, "");             //remove if u want links in your table
        tab_text = tab_text.replace(/<img[^>]*>/gi,"");                 // remove if u want images in your table
        tab_text = tab_text.replace(/<input[^>]*>|<\/input>/gi, "");    // reomves input params
        // console.log(tab_text); // aktivate so see the result (press F12 in browser)

        var ua = window.navigator.userAgent;
        var msie = ua.indexOf("MSIE "); 

         // if Internet Explorer
        if (msie > 0 || !!navigator.userAgent.match(/Trident.*rv\:11\./)) {
            txtArea1.document.open("txt/html","replace");
            txtArea1.document.write(tab_text);
            txtArea1.document.close();
            txtArea1.focus(); 
            sa = txtArea1.document.execCommand("SaveAs", true, "DataTableExport.xls");
        }  
        else // other browser not tested on IE 11
            sa = window.open('data:application/vnd.ms-excel,' + encodeURIComponent(tab_text));  

        return (sa);
    }   

? How can i loop through the rows and check for a checked checkbox. I have tried multiple ways.

If anybody can provide a working fiddle example that would be of great help.