My jQuery
code (extracted from below), isn't working in Flask
{% block scripts %}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0/jquery.min.js" />
<!-- Bootstrap JavaScript -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter- bootstrap/4.0.0-alpha/js/bootstrap.min.js" />
<script src="js/jquery.multi-select.js" />
<script type="text/javascript">
// run pre selected options
$('#pre-selected-options').multiSelect();
</script>
{% endblock %}