How can I check to see if the user is anonymous or logged in from javascript?

Question

I would like to determine whether or not the user is logged in or if they're just anonymous from javascript...

I found this question, but it's php code and I wasn't sure if there is a session variable called logged_in that gets stored on login or if that was just something that person had implemented himself.

Anyone know how I can check to see if the user is logged in from javascript, possibly using ajax?

Edit: I'm running Asp.Net MVC, sorry should have specified

This is so that I can implement a client-side ajax login. When the page loads, I need to know if the user is logged in or not so I can implement something similar to an <asp:LoggedInView> control using jquery.

Thanks,
Matt

Answer 1

You can't read session saved data from JavaScript.

An easy way to do it is to create a JS var from PHP (easier than cookies solution), like this:

if ($_SESSION['logged_in'] == 1) {
    echo '<script type="text/javascript">var logged_in=true;</script>';
} else {
    echo '<script type="text/javascript">var logged_in=false;</script>';
}

Then the JS will simply check the native logged_in var to see if the user is logged in.

<script type="text/javascript">
    if (logged_in) {
        alert("My user is logged in!");
    }
</script>