function init() 
{
    YAHOO.util.Event.addListener("form", "submit", sendFeedback);
}

function sendFeedback(){
    var formObject = document.getElementById('feedbackForm');
    var isValid = true;
    
    var name = YAHOO.util.Dom.get('tbName1').value;
    isValid &= name.length > 0;
    showErrorImage('imgFeedbackNameErr', (name.length > 0) ? 'hidden' : 'visible');
    
    var email = YAHOO.util.Dom.get('tbEmail1').value;
    isValid &= email.length > 0;
    showErrorImage('imgFeedbackMailErr', (email.length > 0) ? 'hidden' : 'visible');
    
    var phone = YAHOO.util.Dom.get('tbPhone1').value;
    isValid &= phone.length > 0;
    showErrorImage('imgFeedbackPhoneErr', (phone.length > 0) ? 'hidden' : 'visible');
    
    var comment = YAHOO.util.Dom.get('tbComment1').value;
    isValid &= comment.length > 0;
    showErrorImage('imgFeedbackCommentErr', (comment.length > 0) ? 'hidden' : 'visible');
    
    if (!isValid)
    {
        return false;
    }
}

function ShowMessage(elemId, visibility, display, message) {
	var div = YAHOO.util.Dom.get(elemId);
	div.style.visibility = visibility;
    div.style.display = display;
	div.innerHTML = message;
}

function showErrorImage(imgId, visibility){
    var img = YAHOO.util.Dom.get(imgId);
    img.style.visibility = visibility;
}

YAHOO.util.Event.addListener(window, "load", init);