The whole backoffice is built in ReactJs to render components and fetch data from .NET Core Controller Actions.
The scenario to use ReactJs is, by create new custom areas. Here is a JavaScript Path property to reference a .jsx file.
eg.:
public string JavaScriptPath { get; set; } = "/resrc/js/areas/friendship-view.jsx";
This file should be a .jsx file to reuse existing react components from NLess.IO.
Many react components are mainly for internal use, but some of the components can be reused to achive a matching design and ux.