JSFiddle - React, Tailwind, and code Playground

HTML

<table summary="">
    <tr>
       <td>
           <table id="myid" some more attributes> <-- i got that id and 
               <tbody>
                   <tr>foo</tr> <---counting
                   <tr>bar</tr> <---counting
               </tbody>
            </table>
         </td>
      </tr>
 </table>

JavaScript

alert($('#myid tbody tr').length);