JSFiddle - React, Tailwind, and code Playground

HTML

<table id='tbl'>
    <tbody>
        <tr>
            <td>
                <p>Cell1</p>
            </td>
            <td>
                <p>Cell2</p>
            </td>
        </tr>
        <tr>
            <td>
                <p>Cell3</p>
            </td>
            <td>
                <p>Cell4</p>
            </td>
        </tr>
    </tbody>
</table>

<input type="button" id="btnAdd" value="Add New Row"></button>

JavaScript

$("#btnAdd").on("click",function(){
       
var $tableBody = $('#tbl').find("tbody"),
        $trLast = $tableBody.find("tr:last"),
        $trNew = $trLast.clone();
		
    $trLast.after($trNew);
});