function ajaxLogin() { 

	if(document.getElementById("j_username").value == '' || document.getElementById("j_password").value == ''){
		Element.update('loginMessage', 'Pseudo/Mot de passe manquant');
		Element.show('loginMessage'); 
		alert('Pseudo/Mot de passe manquant');
	 }else{
	 	Element.update('loginMessage', 'Vérification ...'); 
	    Element.show('loginMessage'); 
	    var opt = { 
	        method: 'post', 
	        postBody: Form.serialize($('loginForm')) + '&ajax=true', 
	        onSuccess: function(response) { 
	            var msg = response.responseText; 
	            if ("error:" == msg.substr(0, 6)) { 
	                var fp = "<font color='red'>" + msg.substring(6, msg.length) + '</font>'; 
	                Element.update('loginMessage', fp); 
	            } else if ("url:" == msg.substr(0, 4)) { 
	                location.href = msg.substring(4, msg.length); 
	            } else if ("message:" == msg.substr(0, 8)) { 
	                Element.update('loginMessage', msg.substring(8, msg.length)); 
	            } 
	        } 
	    } 
		new Ajax.Request(baseHref + '/j_security_check', opt);  
	 }
}
function loginOnEnter(event) {
    if ((event.which && event.which == 13) ||
        (event.keyCode && event.keyCode == 13)) {
        ajaxLogin();
        return false;
    } else {
        return true;
    }
}