마지막 행 input으로 focus

<script>
    var num = "<?=$pn?>";
    num = Number(num); 

    $(document).on("click","button[name=addrow]",function(){        //추가 버튼

    var lines = $('#addrows').val();
    lines = Number(lines);
    lines = lines + 1;

        for(var i=1; i<lines; i++){
         var addStaffText =  ' <tr> ' + ... + ' </tr>';
             
        var trHtml = $( "tr[name=plist]:last" ); 

        trHtml.after(addStaffText);
        num = num + 1;
        }

    });
</script>