fadeout (#hello含む)

HTML

<div id="hello">
  <div id="hello1" class="ka" >123</div>
  <div id="hello2" class="ki">456</div>
  <div id="hello3" class="ki">789</div>
</div>

CSS

div {
  margin: 0.5em;
  padding: 1em;
  border: solid 1px black;
}

#hello1 {
  color: black;
  background-color: #fcc;
  border: solid 1px #f55;
}

JavaScript

'use strict';
jQuery(function (jQuery) {
  jQuery('#hello').on('click', function (event) {
    var target = event.target;

    if (!jQuery(target).hasClass('ka')) {
      jQuery(target).fadeOut('slow');
    }
  });
});