Deploy different versions of web-application

In this hypothetical scenario I have a web-app running on his 1st version, having around 1,000 active users.

I've just finished the 2nd version and would like to test with some users only, what would be the most patterned way to deliver this new version to those clients and have the rest of them still using the 1st?

Considering an application built using Express (Node.js) and deployed to AWS.