Posting data from EJS to Node.js – Nginx

I have an index.html EJS rendered by a koa/Node.js app which contains a javascript snippet to post data about the current page to the same app, to an endpoint to save in a database.

The javascript code ( an AJAX fetch POST) reaches the Node.js endpoint but doesn’t transmit any data. I don’t see any typo in the code.

# index.js
const Koa = require("koa");
const path = require("path");
const render = require("koa-ejs");
const bodyParser = require("koa-bodyparser");
const router = require("./routes/routes.js");

const app = new Koa();

render(app, {
  root: path.join(__dirname, "/views"),
  layout: false,
  viewExt: "html",
});

app
  .use(bodyParser())
  .use(router.routes())
  .use(router.allowedMethods())
  .use(staticCache("./images", { maxAge: 600000 }))
  .listen(PORT, () => {
    console.log(`Running on port ${PORT}`);
  });

In the index.html, I have a button that triggers a POST request to an endpoint (/node/insert) of the koaRouter. The action is to save information about the current page (say, document.location.href) in a Postgres database.

# /views/index.html
[...]
<form id="newRow">
  <input type="submit" value="New row">
</form>
[...]
<script type="module" src="fetch.js" async></script>

where:

# /views/fetch.js
const data = {
  app: "Node",
  url: document.location.href,
  ...
};

document.getElementById("newRow").addEventListener("submit", (e) => {
  e.preventDefault();
  fetch("/node/insert", {
    method: "POST",
    headers: {
      "Content-Type": "application/json; charset-UTF-8",
    },
    body: JSON.stringify(data),
  })
    .then((res) => {
      if (res.ok) {
        return res.json();
      }
      return Promise.reject(res);
    })
    .then((res) => console.log("front", res))
    .catch((err) => console.warn(err));

Among the routes, I defined an endpoint /node/insert to respond to this action:

# routes.js
const koaRouter = require("koa-router");
const router = new koaRouter();

router.post("/node/insert", async (ctx) => {
  console.log("posted", ctx.request.body);   
   ^^^  "posted" is positively printed in terminal after submit

  if (ctx.request.body) {
     return (ctx.response.status = 200)
  } else {
    return (ctx.response.status = 404); <-- check
  }
})

The endpoint "/node/insert" is reached since I can console.log positively, but the body isn’t passed to the endpoint: ctx.request.body = {}. I have the following error:

"SyntaxError: Unexpected token O in JSON at position 0"

detected from fetch.js (probably because the body is {}?).

I don’t see what is wrong.

Note: the Node app runs in a container (pm2-runtime start index.js) and use Nginx as reverse proxy, static files server and load-balancer`