使用XMLHttpRequest只有一个set-cookie值

Creator 2.x
#1

CocosCreator 1.9.3 使用XMLHttpRequest，发送post请求，服务器端返回两个set-cookie值，但是客户端只能解析出一个set-cookie值。是不是没有考虑两个情况？求解答。理论上说如果服务器返回两个，那么客户端收到的set-cookie应该是一个数组，里面包含了两个值，目前还是字符串。该怎么处理？
下面附上代码：

var http_post = function (url, data, callback) {
var xhr = cc.loader.getXMLHttpRequest();
xhr.timeout = 5000;
if (data == null) data = {};
xhr.open(“POST”, url, true);
if (cc.sys.isNative) {
xhr.setRequestHeader(“Accept-Encoding”, “gzip,deflate”, “application/x-www-form-urlencoded;charset=UTF-8”);
}

var timer = setTimeout(function() {
    xhr.hasRetried = true;
    xhr.abort();
    console.log('http timeout');
    retryFunc();
}, 5000);

var retryFunc = function() {
    exports.http_post(url, data, callback);
};

xhr.onreadystatechange = function () {
    clearTimeout(timer);
    if (xhr.readyState === 4 && (xhr.status >= 200 && xhr.status < 300)) {
        cc.log("Object.keys(xhr)");//
        
        //var obj = xhr.getAllResponseHeaders();
        var obj = xhr.getResponseHeader("set-cookie");
        cc.log(obj)

        var respText = xhr.responseText;
        var ret = null;
        try {
            ret = JSON.parse(respText);
        } catch (e) {
            console.log("err:" + e);
        }

        if (callback) {
            callback(ret);
        }
        callback = null;
    }
    else if (xhr.readyState === 4) {
        if(xhr.hasRetried){
            return;
        }
        console.log('other readystate == 4' + ', status:' + xhr.status);
        setTimeout(function() {
            retryFunc();
        }, 5000);
    }
    else {
        console.log('other readystate:' + xhr.readyState + ', status:' + xhr.status);
    }
};

try {
    //cc.log(JSON.stringify(data));
    xhr.send(data);
    //xhr.send(data);
}
catch (e) {
    //setTimeout(retryFunc, 200);
    retryFunc();
}
return xhr;

};