This repo is an example of how to use postmessge to communicate with an iframe.
For more informations, read this [post][post]
To use it, simply run npm install and npm run dev.
Then open a browser window to visit http://localhost:8081/.
[post]:http://blog.lotp.xyz/2016/12/01/How-to-Use-Postmessage-to-Communicate-with-iframe-in-React/