var arr = new Array;

    $("#selectBoxid option").each  ( function() {
       arr.push ( $(this).val() );
    });

alert ( arr.join(',' ) );

$("#btn1").click ( function() {
        var arr = new Array;
        $("#selectBoxid option").each ( function() {
            arr.push ( $(this).val() );
        });
        alert ( arr );
    });