JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<tr>
  <td>
    <select class="mySelect">
      <option value="na"></option>
      <option value="1">value 1</option>
      <option value="2">value 2</option>
    </select> 

    <select class="mySelect">
      <option value="na"></option>
      <option value="3">value 3</option>
      <option value="4">value 4</option>
    </select> 
  </td>
</tr>
<tr>
  <td>
    <input type="button" value="click me" disabled="disabled">
  </td>
</tr>
</table>

JavaScript

$(".mySelect").change(function () {
    var buttonstate = 0;
    $('.mySelect').each(function () {
        if ($(this).val() != 'na') {
            buttonstate++;
        }
    });
    if (buttonstate == 2) {
        $(this).parent().parent().parent().find('input:button').attr("disabled", "");
    } else {
        $(this).parent().parent().parent().find('input:button').attr("disabled", "disabled");
    }
});