function mostraAutor(id,mode){

    var inactiveClass;
    var activeClass;
    if (mode == 'fo') {
        activeClass= "active-fo";
        inactiveClass = "inactive-fo";
    }
    else if (mode == 'es') {
        activeClass = "active-es";
        inactiveClass = "inactive-es";
    }
    else {
        activeClass = "active";
        inactiveClass = "inactive";
    }
    document.getElementById('autor-a').style.display='none';
    document.getElementById('letter-a').className=inactiveClass; 
    document.getElementById('autor-b').style.display='none';
    document.getElementById('letter-b').className=inactiveClass; 
    document.getElementById('autor-c').style.display='none';
    document.getElementById('letter-c').className=inactiveClass; 
    document.getElementById('autor-d').style.display='none';
    document.getElementById('letter-d').className=inactiveClass; 
    document.getElementById('autor-e').style.display='none';
    document.getElementById('letter-e').className=inactiveClass; 
    document.getElementById('autor-f').style.display='none';
    document.getElementById('letter-f').className=inactiveClass; 
    document.getElementById('autor-g').style.display='none';
    document.getElementById('letter-g').className=inactiveClass; 
    document.getElementById('autor-h').style.display='none';
    document.getElementById('letter-h').className=inactiveClass; 
    document.getElementById('autor-i').style.display='none';
    document.getElementById('letter-i').className=inactiveClass; 
    document.getElementById('autor-j').style.display='none';
    document.getElementById('letter-j').className=inactiveClass; 
    document.getElementById('autor-k').style.display='none';
    document.getElementById('letter-k').className=inactiveClass; 
    document.getElementById('autor-l').style.display='none';
    document.getElementById('letter-l').className=inactiveClass; 
    document.getElementById('autor-m').style.display='none';
    document.getElementById('letter-m').className=inactiveClass; 
    document.getElementById('autor-n').style.display='none';
    document.getElementById('letter-n').className=inactiveClass; 
    document.getElementById('autor-o').style.display='none';
    document.getElementById('letter-o').className=inactiveClass; 
    document.getElementById('autor-p').style.display='none';
    document.getElementById('letter-p').className=inactiveClass; 
    document.getElementById('autor-q').style.display='none';
    document.getElementById('letter-q').className=inactiveClass; 
    document.getElementById('autor-r').style.display='none';
    document.getElementById('letter-r').className=inactiveClass; 
    document.getElementById('autor-s').style.display='none';
    document.getElementById('letter-s').className=inactiveClass; 
    document.getElementById('autor-t').style.display='none';
    document.getElementById('letter-t').className=inactiveClass; 
    document.getElementById('autor-u').style.display='none';
    document.getElementById('letter-u').className=inactiveClass; 
    document.getElementById('autor-v').style.display='none';
    document.getElementById('letter-v').className=inactiveClass; 
    document.getElementById('autor-w').style.display='none';
    document.getElementById('letter-w').className=inactiveClass; 
    document.getElementById('autor-x').style.display='none';
    document.getElementById('letter-x').className=inactiveClass; 
    document.getElementById('autor-y').style.display='none';
    document.getElementById('letter-y').className=inactiveClass; 
    document.getElementById('autor-z').style.display='none';
    document.getElementById('letter-z').className=inactiveClass;    
    
    document.getElementById('autor-'+id).style.display='block';
    document.getElementById('letter-'+id).className=activeClass;
}

function isDOMCompliant ()
{
        return (document.getElementsByTagName && document.createElement);
}

function changeElementText (node,text) 
{
    while (node.hasChildNodes()) {
        node.removeChild(node.lastChild);
    }
    var textNode = document.createTextNode(text);
    node.appendChild(textNode );
}

/* --- funcions aux ---- */
function trim(str)
{
    return str.replace(/^\s*|\s*$/g,"");
}
    
function validaNewsletter() {
    var e=true;
    var n=true;
    e=validateEmail('email', 'error-newsletter','msg-newsletter','E-mail inv\340lid', 'Indiqueu l\'e-mail');
    n=validateField('name','error-newsletter','msg-newsletter','Indiqueu el nom', 'Indiqueu el nom');
    if (e!=false) e=true;
    if (n!=false) n=true;
    
    if (e && n) {
        document.getElementById('subscribe').submit();
    }                 
} 

function check_email(e) {
    ok = "1234567890qwertyuiop[]asdfghjklzxcvbnm.@-_QWERTYUIOPASDFGHJKLZXCVBNM";
    
    for(i=0; i < e.length ;i++){
        if(ok.indexOf(e.charAt(i))<0){ 
            return (false);
        }       
    } 
    
    if (document.images) {
        re = /(@.*@)|(\.\.)|(^\.)|(^@)|(@$)|(\.$)|(@\.)/;
        re_two = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/;
        if (!e.match(re) && e.match(re_two)) {
            return (-1);            
        } 
    }
}

function check_field (f)
{
    var field = trim(f);
    if (field.length == 0) {
        return false;
    }
    else {
        return true;
    }
}

function validateEmail(id,msgArea,msg,alertText)
{
    // check the first email address ( the exclamation means "not" )
    field = document.getElementById (id);
    if(!check_email(field.value)){
        showMsg (msgArea,msg,alertText,true);
        // change the color of text field
        field.style.borderColor = "red";
        field.focus(); 
        // make sure the form is not submitted
        return false;
    }
    else {
        return true;
    }
}

function validateField(id,msgArea,msg,alertText,isError)
{
    field = document.getElementById(id);
    if(!check_field(field.value)){
        showMsg(msgArea, msg, alertText,isError);
        // change the color of text field
        field.style.borderColor = "red";
        field.focus();
        // make sure the form is not submitted
        return false;
    }
    else {
        return true;
    }
}

function showMsg (msgArea, msg, msgText,isError)
{
    displayArea = document.getElementById (msgArea);
    displayElement =  document.getElementById (msg);
    displayArea.style.display = "";
    displayElement.style.display = "";
    if (isError) {
        displayArea.style.backgroundColor="#FF6666";
    }
    else {
        displayArea.style.backgroundColor="#FFFF99";    
    }
    if (!isDOMCompliant) {
        alert (msgText);
    }
    else {
        
        changeElementText (displayElement,msgText);
        //document.location.href="#top";    
    }
}