Adding Dynamic ID through jQuery

function addAddressBar(){
 $("#address-div").children('.address-info:last').clone().appendTo("#address-div");
    $(".address-info:last").find('select').val("");
     var len = $("[class*='address-info']").length;
     $('#address-div .address-info:nth-child('+len+') .one').attr( "id", "country_id_"+len ).attr("onChange","ajx_state('"+""+len+"',this.value)");
    $('#address-div .address-info:nth-child('+len+') .two').attr( "id", "state_id_"+len ).attr("onChange","ajx_city('"+""+len+"',this.value)");
    $('#address-div .address-info:nth-child('+len+') .three').attr( "id", "city_id_"+len );
    $("#count_address").val(len);
    return false;
}