React & Redux single-page application authorizing ASP.NET Core web API to call Microsoft Graph using on-behalf-of flow

There's a newer version of this sample taking advantage of MSAL React.

Check it out: React single-page application calling Express.js web API using OAuth 2.0 on-behalf-of flow

If you really need to access this sample, you can navigate to the master branch, but please know that it's no longer maintained.