JSFiddle - React, Tailwind, and code Playground

HTML

<label>How did you hear about us?</label>
<select name="how" class="selectfield" id="how">
  <option value="">Please Select...</option>
  <option value="Advertisement">Advertisement</option>
  <option value="Care at Home Today">Care at Home Today</option>
  <option value="Email-Newsletter">Email/Newsletter</option>
  <option value="Facebook">Facebook</option>
  <option value="Family-Friend">Family or Friend</option>
  <option value="Magazine">Magazine Article</option>
  <option value="Twitter">Twitter</option>
  <option value="Website-Search Engine">Website/Search Engine</option>
  <option value="Other">Other</option>
</select>
<input type='text' id="other" class="hidden" />

<input name="contactus" type="submit" class="submit" id="contactus" value="Submit" />

CSS

.hidden{
   display:none;
}

JavaScript

$('#how').change(function(){
    var selected_item = $(this).val()
    if(selected_item == "Other"){
        $('#other').val("").removeClass('hidden');
    }else{
        $('#other').val(selected_item).addClass('hidden');
    }
});