The mechanism for notifying the client when data changes on the server. Which to choose?

Question

Django

We have python 2.7, mysql, django, nginx, react.js on the client. Tell me
the easiest way to learn how to notify pages from clients that new data has appeared or that another person is currently editing the page.
There are no overloads, millions of parallel connections are not expected. There will be hundreds, maybe thousands, no more.
Nginx has a built-in limit on the frequency of requests from one ip, which does not allow using stupid POST 5 times per second from each client. Disabling the restriction, of course, I do not want to.
There is supposed to be some place on the server where the current code will write the key->key-changed-date pairs. With any change in the data corresponding to the key, the server must somehow report to this place. The client code must subscribe to the keys and, upon detecting a change, reload something from the server.

Answer 1

before the user action (user input, for example) make an ajax request to jang