I haven’t used simple:json-routes before, but I have used Picker in the past. And following code worked for me.
//somewhere on the server
import bodyParser from "body-parser";
Picker.middleware(bodyParser.raw());
Picker.route("/callback/item/:id", (params, req, res) => {
res.setHeader('Content-Type', 'text/html');
let data = '';
req.on('data', (chunk) => {
data += chunk;
});
req.on('end', () => {
console.log('No more data.');
console.log(data);
res.writeHead(200, { 'Content-Type': 'text/plain' });
res.end('ok');
});
});