JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<button onclick="addStr()">Добавить ячейку</button>
<table id="tableResult" style="border:1px solid;">
  <tr>
    <td>11</td>
  </tr>
</table>
</body>

JavaScript

function addStr() {
    var str = document.getElementById('tableResult');
    var add = str.insertRow(-1);
    //add.insertCell(0);
    var addTr = document.createElement("tr");
    var addTd = document.createElement("td");
    addTd.innerHTML="11";
    addTr.appendChild(addTd);
    str.appendChild(addTr);
}