You can find step by step guide for Golang Part 1 here And React Part 2 here to understand this demo properly.

for golang graphql gqlgen package is used. for reacjs applo-client is used.

cd golang
go get ./
go run main.go

cd reactjs
npm install
npm start

Golang graphql server will start on http://localhost:8888

React server will start on http://localhost:3000

Checkout full blog for Golang Part 1 here And React Part 2 here