List all Files in a Directory including files in Subdirectories.

allFiles.js

const allRoutes = ((routeDir, routes) => {
  const routeFiles = fs.readdirSync(routeDir);
  routes = routes || [];
  routeFiles.forEach((file) => {
    if(fs.statSync(routeDir + file).isDirectory()) {
      routes = allRoutes(routeDir + file + '/', routes);
    } else {
      routes.push(file);
    }
  });
  return routes;
});