This example show you how to:
<select id="country_id" class="mSelect" multiple="multiple"></select>
<select id="state_id" class="mSelect" multiple="multiple"></select>
<select id="city_id" class="mSelect" multiple="multiple"></select>
$(function () {
$('#country_id').mSelect({
url: 'ajax/example11.php?q=countries', //load the contry mSelect
loadWhenOpen: true //load the data only when open the mSeelect
});
$('#state_id').mSelect({
url: 'ajax/example11.php?q=states', //load the states mSelect
loadWhenOpen: true
});
$('#city_id').mSelect({
url: 'ajax/example11.php?q=cities', //load the cities mSelect
loadWhenOpen: true
});
});