Validating radio buttons by their boolean values?

Question

I want to avoid using a for loop to validate a set of radio buttons. I know that its possible to use their boolean value to do this I just cannot seem to execute it. Is there a better way to do this?

Here are my buttons:

 <form method="post" name="newUser" onsubmit="return proc()">
            First name:<br />
            <input type="text" id="fName" /><br />
            <div id="first_name_error"></div>
            Last name:<br />
            <input type="text" name="lName" /><br />
            <div id="last_name_error"></div>
            E-mail address:<br />
            <input type="text" name="eMail" /><br />
            <div id="email_error"></div>
            Gender:<input type="radio" name"sex" value="male" />Male
                    <input type="radio" name="sex" value="female" />Female<br />
                     <div id="gender_error"></div>

Here is my JS:

function proc(){
    var errmsg = "";
    if (document.forms["newUser"]["fName"].value == "")
    {
        document.getElementById('first_name_error').innerHTML = "*This field is required";
        document.getElementById('first_name_error').style.color = "red";
    }
    if (document.forms["newUser"]["lName"].value == "")
    {
        document.getElementById('last_name_error').innerHTML = "*This field is required";
        document.getElementById('last_name_error').style.color = "red";
    }
    if (document.forms["newUser"]["eMail"].value == "")
    {
        document.getElementById('email_error').innerHTML = "*This field is required";
        document.getElementById('email_error').style.color = "red";
    }
    if (document.forms["newUser"].sex == false)
    {
        document.getElementById('gender_error').innerHTML = "*Please select gender";
        document.getElementById('gender_error').style.color = "red";

    }

    return false;

}

Answer 1

I think you'd better assign two ids to two radio buttons (radbtnMale, radbtnFemale for example) Then check:

if (document.getElementById("radbtnMale").checked == false && document.getElementById("radbtnFemale").checked == false) {
        document.getElementById('gender_error').innerHTML = "*Please select gender";
        document.getElementById('gender_error').style.color = "red";

} else {
        //
}

Answer 2

Try this (jQuery):

if($('input[name=n]:checked').length==0){
    //error
}else{
    //OK
}