Validate radiobuttonlist using javascript in asp net

Here is the function for validating radiobutton list

to select at least on Item through JavaScript

function validateRadioButtonList(radiobuttonlist_id, msgid) {

    var listItemArray = document.getElementById(radiobuttonlist_id);

    var isItemChecked = false;

    for (var i = 0; i < listItemArray.rows.length; i++) {

        var listItem = document.getElementById(radiobuttonlist_id + "_" + i);

        if (listItem.checked) {

            isItemChecked = true;

        }

    }

    if (isItemChecked == false) {

        document.getElementById(msgid).innerHTML = "Please select atleast oneitem";

        //document.getElementById(error_icon_star).innerHTML='<img src="WebResource.gif" height="15px" style="width:15px;"/>';

        return false;

    }

    document.getElementById(msgid).innerHTML = "&nbsp;";

    //document.getElementById(error_icon_star).innerHTML='<b style="color:Red">*</b>';

    return true;

}