Google Plus Callback

gistfile1.js

gapi.auth.signIn({
    scope: 'email',
    clientid: OATH2_CLIENT_ID,
    callback: 'signinCallback',
    cookiepolicy: 'single_host_origin',
    approvalprompt: auto
});

function signinCallback(authResult){
    if (authResult.status.method === 'AUTO') {
        // when you click "Login" it calls this method 
        // before you confirm your e-mail
        return;
    }
    if (authResult['access_token']) {
        // success
    } else if (authResult['error']) {
        // error
    }
}