How to open a third-party site to a user, and then return it to the original one on command?

Question

JavaScript

There is such a problem.
The user enters the nodejs site, a page is shown to him, he does something, and then, at the command of the server, a third-party site should open to the user, for example, NSA.gov with dynamic content, html5, websockets, and other different third-party site cuisine. And then, according to the server event, the user needs to be returned to the original page of our server.
The user does not need to browse on a third-party site. Display only.
How to do it?

Answer 1

iframe doesn't work?