Some implementation in classes; add JSDOC

app.mjs

@@ -3,7 +3,11 @@ import createError from 'http-errors';
 import logger from 'morgan';
 import express from 'express';
 import path from 'path';
+import * as dotenv from 'dotenv';
 import router from './routes/index.mjs';
+
+dotenv.config();
+
 let indexRouter = router;
 
 let app = express();