function handle_auth_response($response)
{
    if ($response['stat'] == "ok") {
        trigger_error("Authenticated user. UUID: {$response['capture_user']['uuid']}");
        trigger_error("Exchanging authorization code: {$response['authorization_code']}");
        $tokens = janrain_exchange_authorization_code($response['authorization_code']);
        janrain_set_session_data($tokens, $response['capture_user']);
        return array('status' => 'success', 'data' => janrain_get_client_side_session_data());
    } else {
        if ($response['error'] == 'invalid_credentials') {
            return array('status' => 'error', 'message' => $response['invalid_fields']['signInForm'][0], 'code' => $response['code'], 'data' => $response);
        } else {
            return array('status' => 'error', 'message' => $response['error_description'], 'code' => $response['code'], 'data' => $response);
        }
    }
}
<?php

/**
 *  Endpoint to fetch session data that can be exposed client-side.
 *  JSON response.
 */
require_once "janrain.php";
header('Content-Type: application/json');
ini_set('display_errors', False);
session_start();
echo json_encode(array('status' => 'success', 'data' => janrain_get_client_side_session_data()));