javascript append to html table tr

<table id="myTable">
  <tr>
    <td>Row1 cell1</td>
    <td>Row1 cell2</td>
  </tr>
  <tr>
    <td>Row2 cell1</td>
    <td>Row2 cell2</td>
  </tr>
  <tr>
    <td>Row3 cell1</td>
    <td>Row3 cell2</td>
  </tr>
</table>
<button type="button" onclick="myFunction()">Try it</button>

<script>
function myFunction() {
  var table = document.getElementById("myTable");
  var row = table.insertRow(0);
  var cell1 = row.insertCell(0);
  var cell2 = row.insertCell(1);
  cell1.innerHTML = "NEW CELL1";
  cell2.innerHTML = "NEW CELL2";
}
</script>