<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.10/css/select2.min.css" rel="stylesheet" />
<script src="https://code.jquery.com/jquery-1.11.3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.10/js/select2.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$(".chooser").select2({
tags: true,
width: 250
});
$("ul.select2-selection__rendered").sortable({
containment: 'parent'
});
});
</script>
</head>
<body>
<select class="chooser form-control" multiple="multiple">
<option>yellow</option>
<option>blue</option>
<option>purple</option>
<option>red</option>
</select>
</body>