Bootstrap Tagsinput how to get multiple values as an array

Hey guys I have a problem with Bootstrap Tagsinput I'm trying to get an array with all the tags from the input text as values

<input type="text" name="designation" data-role="tagsinput" id="tags_id">

here's the js code

<script>
$('#tags_id').tagsinput('items');
</script>

When i insert some values in the input i get this "123,2131,12" but i need to get somthing like this ["123","2131","12"], and sorry for my english

via Chebli Mohamed