2.2.5.3.14. updateToken(minValidity)

keycloak.updateToken(5)
    .then(function(refreshed) {
        if (refreshed) {
            alert('Token was successfully refreshed');
        } else {
            alert('Token is still valid');
        }
    }).catch(function() {
        alert('Failed to refresh the token, or the session has expired');
    });