JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <thead>
        <tr>
            <th>a</th>
            <th>b</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>1</td>
            <td>2</td>
        </tr>
    </tbody>
</table>

CSS

table, th, td {
   border: 1px solid black;
}

JavaScript

$(function() {
   $( "th:nth-child(2)" ).append( "<span><input type='checkbox'></input> Check all</span>" ); 
});