Google+ JavaScript API: How to detect user sign in status?

Question

I have deployed Google+ Sign-in Button, now I have to provide Sign-Out Button, before that, I need to know whether the user is still signed in, by which I can then show or hide this button.

I found this documentation: gapi.auth.checkSessionState(sessionParams, callback): https://developers.google.com/+/web/api/javascript?hl=en#gapiauthchecksessionstatesessionparams_callback

Could someone demo how to use it ?

Many thanks.

Answer 1

gapi.auth2.getAuthInstance().isSignedIn.get()

This returns boolean

Answer 2

You don't need to use a separate function call to determine the user's signed in state if you've already added the sign-in button. The sign-in button's callback is going to trigger either on sign-in, when the page loads, or any time that the user's signed-in status changes. The page load trigger (immediate mode), will also help to indicate if the user is a Google signed-in user or not.

See monitoring the user's signed in status, which shows the different status fields that you can check (Google signed in, app signed in, or signed out).

Answer 3

From Google dev docs :

If you pass null to sessionParams.session_state, you can check if the user is signed in to Google, whether or not they have previously authorized your app.

So your code will be like this:

gapi.auth.checkSessionState({session_state: null}, function(isUserNotLoggedIn){
    if (isUserNotLoggedIn) {
    // do some stuff
    }
});