Javascript current hour to use specific stylesheet?

I use the following code to get the current hour of the client and to know if it's AM or PM:

<script type="text/javascript">
//get client time
var d = new Date();
if(d.getHours() >= 06 && d.getHours() <= 18){
    var dayStatus = "day";
    document.write("day");
}开发者_如何学Goelse{
    var dayStatus = "night";
    document.write("night");
}
</script>

I figured out how to find out if it's AM or PM for the client but I want to use different css stylesheet whether it's day or night. How could I do this?

This is what I got in my html HEAD so far which obviously does not work, just need to know how to make it work:

<script type="text/javascript">
if(dayStatus = "day"){
    <link href="includes/style.css" rel="stylesheet" type="text/css" />
}else{
    <link href="includes/style2.css" rel="stylesheet" type="text/css" />
}
</script>

You cannot change a (server-side) session using JavaScript. You really need to do this server-side. If you need the clients time, you will need to post it to the server using AJAX. There are, however, two easier ways of doing it:

Client-sided:

if (isDay) {
    document.write('<link type="text/css" rel="stylesheet" href="url/to/day.css" />');
} else {
    document.write('<link type="text/css" rel="stylesheet" href="url/to/night.css" />');
}

Server-sided:

if ($isDay) {
    echo '<link type="text/css" rel="stylesheet" href="url/to/day.css" />';
} else {
    echo '<link type="text/css" rel="stylesheet" href="url/to/night.css" />';
}

Why don't you forget the date calculation on the client, and instead (on page load) make an AJAX call to a PHP script that will determine whether or not to start the session?

This is possible, will your users be on the same page for a long period of time or be moving around? If they are moving around then simply have the PHP function that will execute on the page load and then determine if to create a new session. Or if not then run a Javascript function on a timer that sends a GET request to a php script which then determines if to create a new session.