$(function(){
        var state = aux_state('aux1');
        alert(state);  // LINE 1
        $('#aux1').switchbutton({
            checked: aux_state('aux1'),
            onChange: function(checked){
                $.get(host +'/set_aux/aux1/'+ checked, function(state){
                    // ...
                });
            }
        });
    });

    function aux_state(aux){
        $.get(host +'/get_aux/' + aux, function(state){
            alert(state); // LINE 2
            return state;
        });
    }