How to create a support chat?

Question

Node.js

The task is to implement a support chat with the ability to embed it on any other site.
Involving technologies react/redux, node, mongo (sometimes sql), socket.io...
How to implement inserting a script into a page?
iframe or is it possible just by inserting elements into the dom?
How to determine that a new connection has been created (chat room), the user has entered the site and opened a chat?
sample application: https://www.jivochat.ru/

Answer 1

Here you will have an application of 2 parts: server and client.
1) It is not necessary to use an iframe to insert into the site, because you can add the assembly bundle somewhere in the body of the site with a script and implement it with a small fixed popup.
2) When entering the page, the autoatom user sends a connection request. It happens:
* Connection to the socket server.
* Adding a user to a room.
As I understand it, since the site will be inserted a lot - where, and we have one server, then we need to somehow bind a specific user to a room, or save a unique room identifier in the url, where the user could continue communicating with those. support. Or request some kind of data, such as mail. Or it will be agreed that when leaving the page, the user loses the progress of communication.

Answer 2

What is the budget (money, time is not important)?
What do you end up wanting?
Why not https://www.jivochat.ru/ ?