function validateRadio(field, alertText)
{
    var ok = false;
    for (var i=0; i < document.getElementsByName(field).length; i++)
        if (document.getElementsByName(field)[i].checked)
            ok = true;
    if (!ok)
    {
        alert(alertText);
        document.getElementsByName(field)[0].focus();
    }
    return ok;
}

function validateTxt(field, alertText)
{
    if (document.getElementsByName(field)[0].value == '')
    {
        alert(alertText);
        document.getElementsByName(field)[0].focus();
        return false;
    }
    else
        return true;
}

function validateChbox(field, alertText)
{
    if (!document.getElementsByName(field)[0].checked)
    {
        alert(alertText);
        document.getElementsByName(field)[0].focus();
        return false;
    }
    else
        return true;
}


function validateEmail(field, alertText)
{
    var emailRegExp = /^[A-Za-z0-9._\-]+@[A-Za-z0-9]([A-Za-z0-9._\-]*\.)+[A-Za-z]+$/;
     if (!emailRegExp.test(document.getElementsByName(field)[0].value))
     {
        alert(alertText);
        document.getElementsByName(field)[0].focus();
        return false;
     }
     else
        return true;
}

function chkf()
{
    if      (!validateTxt('inp_name', 'Fill in the name')) return false;
 	else if (!validateEmail('inp_email', 'Fill in e-mail address')) return false;
    else if (!validateTxt('inp_txt', 'Ask the question')) return false;
    else return true;
}