Frank de Jonge has posted a tutorial to his site showing how you can render React.js templates server-side in PHP. He makes use of the V8JS extension to execute Javascript inside of PHP and echo out the rendered result.
The last couple of months I've been working with ReactJS quite extensively. It's been a very rewarding and insightful journey. There is, however, one part that kept coming back to me: server-side rendering. How on earth am I going to use ReactJS when I want to render my templates on the server? So, I sat down and looked at the possibilities.
He suggests two options, running a small Node application or using the V8JS extension, and opts for trying the second option to meet his needs. He talks about the "why" of rendering server-side JS and gives a brief introduction to V8JS and the workflow he'll follow to use it. He helps you get this library via Composer to make working with it easier and provides an example of how to use it. After trying out this method, he then goes back to option #1, the small Node application (what he ended up choosing). He walks through the setup of this application, showing how to set it up inside a Lumen application and using Express to output the generated templates and data. He then hooks this into the PHP application via a simple HTTP client grabbing the results and pushing them back out to the page.