Validate radiobuttonlist in javascript

Here is the function for validating radiobutton list to select at least on Item through JavaScript radio button list is a ollection of rediobuttons so we have to navigate all sub radio button and check that if selected or not.

just copy and paste the code given bellow and pass the the parameter that is id of radio button.

function validateRadioButtonList(rblId) {

    var listItemArray = document.getElementsByName(rblId);

    var isItemChecked = false;

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

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

        if (listItem.checked) {

            isItemChecked = true;

        }

    }

    if (isItemChecked == false) {

        alert("Please select atleast one item");

        return false;

    }

}