select2/docs/_includes/options/dropdown/selections.html

<section>
  <h2>
    Can I change how selecting results works?
  </h2>

  <h3>
    Can I select the highlighted result when the dropdown is closed?
  </h3>

<pre class="prettyprint">
$('select').select2({
  selectOnClose: true
});
</pre>

  {% include options/not-written.html %}

  <h3>
    Can I prevent the dropdown from closing when a result is selected?
  </h3>

<pre class="prettyprint">
$('select').select2({
  closeOnSelect: false
});
</pre>

  {% include options/not-written.html %}
</section>