how to integrate google 2 factor / 2 step authentication in react app

Question

1. I want to add google 2fa authentication for my react app. How can I generate QR code for my app?
2. Will this be a static or a dynamic code?
3. Where do I need to send the secret (6 digit / 8 digit) code for authentication once the user copies it from the google-authenticator mobile app.
4. what google-api need to be enabled for this app in the console.google.developer.com, like we enable G+ api for google sign-in?

need help!

Resurrectionist