select2 multi select
######## In your HTML:
<select class="js-example-basic-multiple" name="states[]" multiple="multiple">
<option value="AL">Alabama</option>
...
<option value="WY">Wyoming</option>
</select>
####### In your Javascript (external .js resource or <script> tag):
$(document).ready(function() {
$('.js-example-basic-multiple').select2();
});
######### Get Selected values
$('.js-example-basic-multiple').select2('val')
######## Pre select values on page loads
$('.js-example-basic-multiple').val(['AL', 'WY']).trigger('change');