JavaScript Re-Order Table Rows Number

https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_sort_table

<table>
 <tr>
 <td>3</td>
 </tr>
 <tr>
 <td>1</td>
</tr>
 <tr>
 <td>2</td>
 </tr>
</table>

Array.prototype.forEach.call(document.querySelectorAll('td:first-child'), function (elem, idx) {
    elem.innerHTML = idx + 1;
});