Getting username and group from JIRA in Javascript (via REST)

<script type="text/javascript">
var user;
     AJS.$.ajax({
        url: "/rest/gadget/1.0/currentUser",
        type: 'get',
        dataType: 'json',
        async: false,
        success: function(data) {
            user = data.username;
        }
     });
     alert(user);
</script>

<script type="text/javascript">
var user;
     AJS.$.ajax({
        url: "/rest/gadget/1.0/currentUser",
        type: 'get',
        dataType: 'json',
        async: false,
        success: function(data) {
            user = data.username;
        }
     });
var groups;
     AJS.$.ajax({
        url: "/rest/api/2/user?username="+user+"&expand=groups",
        type: 'get',
        dataType: 'json',
        async: false,
        success: function(data) {
            groups = data.groups.items;
        }
     });
     alert(groups);
</script>