Implement swagger-autogen with the Nodejs (IIFE)

Question

I am trying to implement the swagger-autogen with the nodejs where my code in nodejs written in Immediately Invoked Function Expressions (IIFE) type.It is not giving the desired output. the swagger-output.json file is not having any api's.

Here is my app.js

const app = express();

app.use(helmet());
app.use(express.static(path.join(__dirname, "public")));
app.use(cookieParser());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

require("./routes").connectRoutes(app);

app.listen(port, () => {
  console.log("app listening on port " + port);
});

here is my routes.js

(() => {

  function connectRoutes(app) {
    app.enable("strict routing");
    app.use(initialLogging);
    app.use("/api/v1/", require("./route_handlers/auth"));
  }

  function initialLogging(req, res, next) {
    var path = (req.method || "") + ":" + (req.originalUrl || "utils/error_utils");
    const logger = require("./utils/logging_utils")(path);
    logger.info("About to call");
    next();
  }
  module.exports.connectRoutes = connectRoutes;
})();

I tried to implement the swagger-autogen but it is not giving any output.

i am using "swagger-autogen": "^2.23.5", express - "express": "^4.17.1",

my swagger.js file

const swaggerAutogen = require("swagger-autogen")();

const doc = {
  info: {
    title: appName,
    description: appDesc,
  },
  host: "localhost:5001",
  basePath: "/",
  schemes: ["http", "https"],
  consumes: ["application/json"],
  produces: ["application/json"],
  tags: [
    {
      name: appName,
      description: appDesc,
    },
  ],
};


let outputFile = "./public/api-docs/swagger-output1.json";
if (!fs.existsSync(outputFile)) {
  outputFile = fs.openSync(outputFile, "w");
}
const endpointsFiles = ["./routes.js"];
swaggerAutogen(outputFile, endpointsFiles, doc);