Question

I want to reset new values each time in the option list created JSON by the line:

var o=document.createElement("option");
document.getElementById("shipTo").options.add(o); 
o.text= address[i];

But new option values are added in the list I want the no previous in the option:

var counter;
function GetAddress() {
    var customerId = document.getElementById("invoiceTo").value;
    var xml;
    if (window.XMLHttpRequest) {
        xml = new XMLHttpRequest();
    } else {
        xml = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xml.onreadystatechange = function() {
        if (xml.readyState == 4 && xml.status == 200) {
            var address = JSON.parse(xml.responseText);
            document.getElementById("billingAddress").value = address[0];
            document.getElementById("shipAddress").value = address[0];
            if (counter == 1) { {
                    for (var i = 0; i < address.length; i++) {
                        var removeMe = document.getElementById(o[i]);
                        removeMe.parentNode.removeChild(removeMe);
                        var o = document.createElement("option");
                        document.getElementById("shipTo").options.add(o);
                        o.text = address[i];
                    }
                }
            } else if (counter != 1) {
                for (var i = 0; i < address.length; i++) {
                    var o = document.createElement("option");
                    document.getElementById("shipTo").options.add(o);
                    o.text = address[i];
                }
            }
            counter = 1;
        }
        alert(counter);
    }
    xml.open("GET", "GenerateInvoice?customerId=" + customerId, true);
    xml.send();
}

Answer 1

You need to clear the options first:

var oDDL = document.getElementById("shipTo");
while (oDDL.options.length > 0)
    oDDL.options.remove(0);