title: Detect if a web user is currently logged in Google?
body: <p>Suppose I want to display certain content only if I know the user coming to my website has a valid Google Account and it's logged into that account.</p>
  
  <p>Is there any way to do this in Javascript? I know that the Facebook API provides ways to tell the status of a user (logged in Facebook) and I'm sure I've seen sites doing this with Google Accounts as well, but searching for the relevant terms in Google leads me to nowhere as the search terms are poorly focused.</p>
  
  <p>Thank you for any help.</p>