FB.logout() called without an access token

Question

I'm trying to log out of a website i've created with Facebook integrated. Logging in works fine, but when I want to log out Firebug consistently gives me this error:

FB.logout() called without an access token.

I'm using the Facebook JavaScript SDK, and the code I've got to logout looks like this:

$(document).ready($(function () {
    $("#fblogout").click(facebooklogout);
}));

function facebooklogout() {
    FB.logout(function (response) {
    }
)};

This is the logout code specified at the Facebook Developers Documentation just with a button being assigned the method on document.ready

Before this code I have the FB.init() method, that all runs fine.

If anyone's got a solution as to why FB.logout doesn't have an access token, it'd be appreciated.

Answer 1

The error says that you don't have an access token, you have to check for one using the FB.getAccessToken() function.

If there is no access token the function returns null. See example below:

   function facebooklogout() {
    try {
        if (FB.getAccessToken() != null) {
            FB.logout(function(response) {
                // user is now logged out from facebook do your post request or just redirect
                window.location.replace(href);
            });
        } else {
            // user is not logged in with facebook, maybe with something else
            window.location.replace(href);
        }
    } catch (err) {
        // any errors just logout
        window.location.replace(href);
    }
   }

Answer 2

I went for the less trivial solution:

    function facebookLogout(){
        FB.getLoginStatus(function(response) {
            if (response.status === 'connected') {
                FB.logout(function(response) {
                    // this part just clears the $_SESSION var
                    // replace with your own code
                    $.post("/logout").done(function() {
                        $('#status').html('<p>Logged out.</p>');
                    });
                });
            }
        });
    }

Answer 3

I've tried something like this:

function fbLogout(){
    if(typeof FB.logout == 'function'){
        if (FB.getAuthResponse()) {
         FB.logout(function(response) { window.location.href = PROJECT_PATH + '/index/logout'; }); 
         return;
        }  
    };

    window.location.href = PROJECT_PATH + '/index/logout'; 
    return;  
}

Answer 4

To logout from the application which uses facebook graph API, use this JavaScript on the logout page just after the <form> tag:

window.onload=function()
{
    // initialize the library with your Facebook API key
    FB.init({ apiKey: 'b65c1efa72f570xxxxxxxxxxxxxxxxx' });

    //Fetch the status so that we can log out.
    //You must have the login status before you can logout,
    //and if you authenticated via oAuth (server side), this is necessary.
    //If you logged in via the JavaScript SDK, you can simply call FB.logout()
    //once the login status is fetched, call handleSessionResponse
    FB.getLoginStatus(handleSessionResponse);
}

//handle a session response from any of the auth related calls
function handleSessionResponse(response) {
    //if we dont have a session (which means the user has been logged out, redirect the user)
    if (!response.session) {
        window.location = "/mysite/Login.aspx";
        return;
    }

    //if we do have a non-null response.session, call FB.logout(),
    //the JS method will log the user out of Facebook and remove any authorization cookies
    FB.logout(handleSessionResponse);
}

The code works and is live on my site.

Answer 5

Should be something more like this. There was a change to the JS API where you have to use authResponse instead of just session.

//handle a session response from any of the auth related calls
function handleSessionResponse(response) {

    //if we dont have a session (which means the user has been logged out, redirect the user)
    if (!response.authResponse) {
        return;
    }

    //if we do have a non-null response.session, call FB.logout(),
    //the JS method will log the user out of Facebook and remove any authorization cookies
    FB.logout(response.authResponse);
}