How to verify jwt token in server side by google identity services

[Shiv_Pandey]

Hello, I am creating a simple react js application with google login authentication and I use the new(GSI) one to authenticate users. Everything works fine when the google authentication is used as a popup. After that, I use the ux_mode: redirect method, and then I create a server that catches the post request but there I didn't find any way to very my token. How can I do it please someone helps me...... 

Kindly check the screenshot.
NODE JS (index.js)

Reactjs