Why is null arriving?

Question

Node.js

Hello. I created the simplest server, GET requests work, but there is some kind of trouble with POST.

Server code:

const express = require("express");
const cors = require("cors");

const app = express();

const PORT = process.env.PORT || 80;

app.listen(PORT, () => {
  try {
    console.log(`Server started on ${PORT}...`);
  } catch (e) {
    console.error(`${e} - app.listen`);
  }
});

const userList = [];
const userData = [];

app.get("/userList", (req, res) => {
  try {
    res.send(userList);
  } catch (e) {
    console.error(`${e} - app.get("/userList")`);
  }
});

app.get("/userData", (req, res) => {
  try {
    res.send(userData);
  } catch (e) {
    console.error(`${e} - app.get("/userData")`);
  }
});

app.post("/userData", (req, res) => {
  try {
    userData = req.body;
  } catch (e) {
    console.error(`${e} - app.post("/userData")`);
  }
});

app.post("/userList", (req, res) => {
  try {
    userList.push(req.body);
  } catch (e) {
    console.error(`${e} - app.post("/userList")`);
  }
});

app.use(cors());

Application code with POST request:

const axios = require("axios");
const postUrl = "https://stormy-gorge-63462.herokuapp.com/userList";
axios.post(postUrl, {
  firstName: "Fredd",
  lastName: "Flint",
});

But for some reason, I catch on the server every time null is added to the array.



Tell me, please, what is the problem?

I apologize in advance for such an amateurish approach, this is my first attempt at working with express and nodeJs