javascript selected radio

Question

I want to check what is the selected radio input.

here is my code.

<input name="u_type" type="radio" value="staff" id="u_type" checked="checked" /> Staff
<input name="u_type" type="radio" value="admin" id="u_type" /> Admin
<input id="add_user" name="add_user" type="button" onclick="addUser();"  value="Add" class="submitButton admin_add" />

function addUser()
{
//how to check what is the selected radio input
}

thanks.

Answer 1

function addUser() {
    //how to check what is the selected radio input
    alert(getCheckedRadioValue('u_type'));
}

function getCheckedRadioValue(name) {
    var elements = document.getElementsByName(name);

    for (var i=0, len=elements.length; i<len; ++i)
        if (elements[i].checked) return elements[i].value;
}

And element's IDs must be different.