Get Radio Button Value in JavaScript

Get Radio Button Value in JavaScript
<script>

function getvalue() {
    var radios = document.getElementsByName("test");

    for (var i = 0; i < radios.length; i++) {      
        if (radios[i].checked) {
            alert(radios[i].value);
            break;
        }
    }
}
</script>
<input type="radio" name="test" value="first" onclick="getvalue();">
<input type="radio" name="test" value="second" onclick="getvalue();">