JSFiddle - React, Tailwind, and code Playground

HTML

<select>
  <option>One</option>
  <option>Two</option>
  <option>Three</option>
  <option value="other">Other...</option>
</select>
<input type="text" size="20" style="display: inline;">

JavaScript

$(document).ready(function() {
  $('input').hide();
  $('select').change(function() {
    if (this.value == 'other') {
      $('input').show();
    }
    else {
      $('input').hide();
    }
  });
});