添加到使用JavaScript

Question

我有

<table id="tbl_dtl">
<tr class = "table_print" id="sub_klp_row<?php echo $index;   ?>">
    <td id="sub_klp<?php echo $index;   ?>" class = "style6" ><?php echo    isset($sub_klp) ? $sub_klp : 'SUB KLP'   ?> </td>
</tr>
<table>

因为我需要使用if条件我想在下面使用javascript添加<td>代码

    <td id="sub_klp<?php echo $index;   ?>" class = "style6" ><?php echo    isset($sub_klp) ? $sub_klp : 'SUB KLP'   ?> </td>

到目前为止我已经做了什么

 if (current_sub_klp.trim() != previous_sub_klp.trim()) {
    //console.log(current_sub_klp); 
    var row = document.getElementsByClassName("sub_klp_row<?php echo $index; ?>");
    var td = document.createElement("td");
    td.name = "sub_klp<?php echo $index; ?>";
    td.id = "sub_klp<?php echo $index; ?>";
    row.appendChild(td);
}