JSFiddle - React, Tailwind, and code Playground

HTML

<table id="table-1" cellspacing="0" cellpadding="2">
    <tr><td>1</td></tr>
    <tr><td>2</td></tr>
    <tr><td>3</td></tr>
    <tr><td>4</td></tr>
    <tr><td>5</td></tr>
    <tr><td>6</td></tr>
</table>

JavaScript

var len = $('#table-1 tr').length;
var $first = $('#table-1 tr').eq(0);
for(var i = 1; i < len; i++) {
    $('#table-1 tr').eq(1).find('td').prependTo($first);
    $('#table-1 tr').eq(1).remove();
}