index.js

const express = require("express");
const EventEmitter = require("events");
const path = require("path");
const cors = require("cors");
const rateLimit = require("express-rate-limit");
//const helmet = require('helmet');
const mongoSanitize = require("express-mongo-sanitize");
const xss = require("xss-clean");
const connectDB = require("./db/mongoose");
//require('./controller/scheduledTask');

//routes constants
const userRoutes = require("./routers/user");
const subjectRoutes = require("./routers/subject");
const attendanceRoutes = require("./routers/attendance");
const { builtinModules } = require("module");

const app = express();

//set security HTTP headers
/*app.use(helmet({
  contentSecurityPolicy: {
    scriptSrc:["'self'", "https://salty-brook-29410.herokuapp.com/"],
  }
}));*/

//conect db
connectDB();
//limit requests from same IP
const limiter = rateLimit({
  max: 100,
  windowMs: 60 * 60 * 1000,
  message: "To many request from this IP, please try again after an hour!",
});

app.use("/", limiter);

app.use(express.json());

//data sanitization against noSQL query injection
app.use(mongoSanitize());

//data sanitization against xss
app.use(xss());

//event emmiter increased
const emitter = new EventEmitter();
emitter.setMaxListeners(20);
app.use(cors());

//Routers
app.use(userRoutes);
app.use(subjectRoutes);
app.use(attendanceRoutes);

//Serve static assets if in Production
if (process.env.NODE_ENV === "production") {
  app.use(express.static("client/build"));

  app.get("*", (req, res) => {
    res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
  });
}

const PORT = process.env.PORT;

app.listen(PORT, () => {
  console.log("APP IS RUNNING ON PORT " + PORT);
});