Craft\ElementApiPlugin::registerSiteRoutes PHP Method

    public function registerSiteRoutes()
    {
        $routes = [];
        $endpoints = craft()->config->get('endpoints', 'elementapi');
        foreach ($endpoints as $pattern => $config) {
            // Convert Yii 2-style route subpatterns to normal regex subpatterns
            $pattern = preg_replace('/<(\\w+):([^>]+)>/', '(?P<\\1>\\2)', $pattern);
            if (is_callable($config)) {
                $params = ['configFactory' => $config];
            } else {
                $params = ['config' => $config];
            }
            $routes[$pattern] = ['action' => 'elementApi/getElements', 'params' => $params];
        }
        return $routes;
    }