function doSelectOk() {        var objSelected = document.getElementById("lbUserSelected");        var selectItemCount = objSelected.options.length;        var objhfSelectIDList = document.getElementById("hfSelectIDList");        var returnValue = "";        var returnText = "";        for (var i = 0; i < selectItemCount; i++) {            var optionValue = objSelected.options[i].value;            var optionText = objSelected.options[i].text;            if (!IsNull(returnValue)) {                returnValue += ",";                returnText += ",";            }            returnValue += optionValue;            returnText += optionText;        }    var objResult = param;        objhfSelectIDList.valve = param.ValueParam;        alert(objhfSelectIDList.valve);        window.returnValue = objResult;        window.close();    }頁面：通過<asp:HiddenField runat="server" />傳值在后臺里 string IDList = hfSelectIDList.Value.Trim(); 不知道為啥IDList 老是為空！請大家幫忙解決一下哈 謝謝！?。?