JSFiddle - React, Tailwind, and code Playground

HTML

<select id="event_category_id" name="event_category_id">
  <option value="">Select Category</option>
  <option value="1">Category One</option>
  <option value="2">Category Two</option>
  <option value="3">Category Three</option>
</select>

JavaScript

$('#event_category_id').change( function(e) {    
   alert( $(this).find(':selected').text() ); 
});