[jQuery] How to test/filter for all divs being hidden ?

[jQuery] How to test/filter for all divs being hidden ?


Hello I am a beginner to jquery/javascript and I am trying to use a
script I saw online to replace the content of a div. However I would
like to have the script start with none of the target content showing.
So far it starts correctly however I am not sure how to test/filter
for ALL the divs in #content being hidden which would be the begging
state of the page.
Here is a link to what it is doing now.
http://noworriestech.com/jquery/indext2.html
Here is the code
<script type="text/javascript">
        $(function(){
            $("#home-button").css({
                opacity: 0.3
            });
            $("#about-button").css({
                opacity: 0.3
            });
            $("#contact-button").css({
                opacity: 0.3
            });
            $("#page-wrap div.button").click(function(){
                $clicked = $(this);
                // if the button is not already "transformed" AND is not animated
                if ($clicked.css("opacity") != "1" && $clicked.is(":not
(animated)")) {
                    $clicked.animate({
                        opacity: 1,
                        borderWidth: 5
                    }, 600 );
                    // each button div MUST have a "xx-button" and the target div
must have an id "xx"
                    var idToLoad = $clicked.attr("id").split('-');
                    if ($("#content > div").is(":hidden")) {
                    $("#content").find("#"+idToLoad[0]).fadeIn();
                    }
                    else {
                    //we search trough the content for the visible div and we fade it
out
                    $("#content").find("div:visible").fadeOut("fast", function(){
                        //once the fade out is completed, we start to fade in the right
div
                        $(this).parent().find("#"+idToLoad[0]).fadeIn();
                    })}
                }
                //we reset the other buttons to default style
                $clicked.siblings(".button").animate({
                    opacity: 0.5,
                    borderWidth: 1
                }, 600 );
            });
        });
    </script>
Thank you for you assitance in advance.