jQuery addClass example

Change class name on click in jQuery

HTML

<form name="form10" id="my_form10" method="post" action="" >
  <h5>Wil je keukenplinten laten inkorten na het leggen van de vloer?</h5>
  <div class="radio8">
    <div class="janee">
      <input id="JA7" type="radio" name="group8" value="Ja">
      <label for="JA7" class="form-field__radio__label">Ja, meerprijs € 20.00 per plint</label><br>
      <input id="NEE7" type="radio" name="group8" value="Nee">
      <label for="NEE7">Nee</label>
      <br>
      <input id="JA8" type="radio" name="group8" value="Ja">
      <label for="JA8" class="form-field__radio__label">Ja, meerprijs € 20.00 per plint</label><br>
    </div>
  </div>
</form>

<form id="keukenplinten">
  <div id="form_JA7" class="desc" style="float: inherit;">
    <h5>Hoeveel keukenplinten wil je laten inkorten?</h5>
    <input type="number" id="keukenplintenInkorten" name="keukenplinten">
  </div>
  <div id="form_JA8" class="desc" style="float: inherit;">
   Ja, meerprijs € 20.00 per 
  </div>
</form>

CSS

.desc {
  display: none;
}

JavaScript

$( document ).ready( function () {
  $( "input[name=group8" ).change( function() {
    var test8 = $(this).attr('id')
    $( ".desc" ).hide();
    $( "#form_"  + test8 ).show();
  } );
} );