[Wiki] Checking for "expired" sessions/logins on the client side

/**
     * Monitor if session expired; show jQuery dialog when it did expire.
     * 
     * Call this somewhere in the page generation process (e.g., in the layout).
     * 
     * @param int $timeout Time between checks in seconds.
     */
    public static function MonitorSessionJQueryDialog($timeout=2) {
        Yii::app()->clientScript->registerCoreScript('jquery-ui');
        $title=CJavaScript::encode(Yii::t('app','Session Expired'));
        $msg=CJavaScript::encode(CHtml::tag('div',array(),Yii::t('app','Your session expired and this page must be reloaded.')));
        $btReload=CJavaScript::encode(Yii::t('app','Reload'));
        $btClose=CJavaScript::encode(Yii::t('app','Close'));
        $jsActionCode="var _ok=false;jQuery($msg).dialog({modal:true,closeOnEscape:false,title:$title,beforeclose:function(){return _ok;},buttons:{ $btClose :function(){_ok=true;jQuery(this).dialog('close');window.open(location.href, '_self').close(); }, $btReload:function(){_ok=true;jQuery(this).dialog('close');location.reload(true);}}});";
        self::MonitorSession($timeout,$jsActionCode);
    }
    /**
     * Monitor if session expired, do some JavaScript action when it does expire.
     *
     * Call this somewhere in the page generation process (e.g., in the layout).
     *
     * @param int $timeout Time between checks in seconds.
     * @param string $jsActionCode JavaScript action code to do; defaults to alert
     *                             popup followad by page reload.
     */
    public static function MonitorSession($timeoutSeconds=2,$jsActionCode=null) {
        $timeoutMs=$timeoutSeconds*1000;
        Yii::app()->clientScript->registerCoreScript('jquery');
        $md5=md5("MonitorSession".Yii::app()->user->getId());
 
        $name=md5(Yii::app()->id."uid");
        if(!Yii::app()->request->cookies->contains('name')) {
            $cookie = new CHttpCookie($name, $md5);
            Yii::app()->request->cookies->add($name, $cookie);
        } else {
            Yii::app()->request->cookies[$name]->value=$md5;
        }
 
        if($jsActionCode===null) {
            $expiredMessage=CJavaScript::encode(Yii::t('app','Your session expired and this page must be reloaded.'));
            $jsActionCode=<<<EOJS
                     alert($expiredMessage);
                     location.reload(true);
EOJS;
        }
        /* @var string $checkCode JavaScript code that checks the conditions (result in check).*/
        $checkCode="";
        if(!Yii::app()->user->getIsGuest()) {
            $stateCookieKey = Yii::app()->user->getStateKeyPrefix();
            $checkCode.=<<<EOJS
                if($.cookie) {
                    var id=$.cookie('$name');
                    var key=$.cookie('$stateCookieKey');
                    check|=(id===null||!id.match('$md5'));
                    check|=(key===null);
                }
EOJS;
        }
        if(Yii::app()->request->enableCsrfValidation) {
            $csrfTokenName = CJavaScript::encode(Yii::app()->request->csrfTokenName);
            $csrfTokenValueRegex= CJavaScript::encode('"'.Yii::app()->request->csrfToken.'"');
 
            $checkCode.=<<<EOJS
                if($.cookie) {
                    var csrf=$.cookie($csrfTokenName);
                    check|=(csrf===null||!csrf.match($csrfTokenValueRegex));
                }
EOJS;
        }
        if($checkCode!=="") {
            $jsMonitorScript=<<<EOJS
                    (function($) {
                        "strict";
                        var timer;
                        function checkSession() {
                            var check=false;
                            $checkCode
                            if(check) {
                                window.clearInterval(timer);
                                $jsActionCode
                            }
                        }
                        function startCheck(){
                            timer=window.setInterval(checkSession,$timeoutMs);
                        }
                        window.onbeforeunload=function(e){
                            window.clearInterval(timer);
                        }
                        window.setTimeout(startCheck,5000);
                    })(jQuery);
EOJS;
            Yii::app()->clientScript->registerScript(__FILE__."#MonitorSession", $jsMonitorScript,CClientScript::POS_READY);
        }
    }