ReactJS is a JavaScript front end for developing end user interfaces. Breaking this down by architectural layer
- JavaScript runs in the Application layer of the OSI, inside of a Browser. The Transport is handled by HTTP for communication to and from a remote web server/application server host..
- Regarding Transport, HTTP Layer Virtual User
- Regarding JavaScript Inside of Browser, TruClient Virtual User
- Regarding Application Layer, browser interaction, GUI Virtual User
- Regarding Virtualized Client OS, Citrix or Remote Desktop Protocol (RDP) Virtual User
The Architecture, or the bones, of your ReactJS framework are fully supported by LoadRunner.
So, yes, you can test applications with user interfaces developed using the ReactJS framework. I might suggest that you begin addressing questions of performance in the development and functional test stages, using the build in developer tools and profilers inside of the browser so you can get an incredibly accurate picture of the in-browser overhead (in short, local processing and rendering time) before you begin answering questions on server scalability. If your application is not performant for one, then it can never be performant for many.