mostrar un listado php con ajax

[Dradi7]

Primero ordenemos tu codigo porque asi no entiendo nada

Código Javascript:

function save() {
 
    ajax=objetoAjax();
    ajax.onreadystatechange=function() {
        if (ajax.readyState==4) {
            alert("se introdujo con exito en la base de datos");
            if(ajax.status==200) 
            {
                ajaxlistar=otroObjetoAjax();
                ajax.open("POST","circuit_actual.php",true);
                ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
            }
        }
    }
    
    var cityvalue=encodeURIComponent(document.getElementById('city').value);
    var arrivalvalue=encodeURIComponent(document.getElementById('datepicker_value').value);
    var departurevalue=encodeURIComponent(document.getElementById('otrodatepicker_value').value);
    var commentvalue=encodeURIComponent(document.getElementById('comment').value);
 
    if(arrivalvalue>departurevalue)
    {
        alert('Day of arrival can not be after a day of departure');
    }
    else if(departurevalue<arrivalvalue)
    {
        alert('Day of departure can not be until the arrival day');
    }
    else{
 
        ajax.open("GET", "addCity.php?city="+cityvalue+"&arrival="+arrivalvalue+"&departure="+departurevalue+"&comment="+commentvalue,true);
        ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        //enviando los valores
        ajax.send();
    
        document.getElementById('savecity').disabled = true;
        document.getElementById('more').disabled = true; 
        document.getElementById('ciudad').value = "Select other city";
        document.getElementById('add').disabled = false;
        document.getElementById('inner').style.display="block";
        document.getElementById('datepicker_value').value='';
        document.getElementById('otrodatepicker_value').value='';
        document.getElementById('comment').value='';
    }
}