Phoenix 1.4 ships with Webpack by default so React is now 100% at home in your next Phoenix project, here is how to get started. The goal of this guide is to get one React component rendering, nothing more.

I was fumbling around until I found this https://www.valentinog.com/blog/react-webpack-babel/

Create your new Phoenix project and enter it

mix phx.new react_on_phoenix --no-ecto # Skipping the database to keep this guide as short as possible
cd react_on_phoenix

Create a new Git repo and make your first commit.

I always do this immediately after running some generation command that I don’t want to have to run again.

git init
git add .
git commit -m 'initial commit'

Pull in the dependencies

As show by https://www.valentinog.com/blog/react-webpack-babel/

cd assets # this is the front-end directory that was set up by Phoenix 1.4
npm i @babel/core babel-loader @babel/preset-env @babel/preset-react react react-dom --save-dev

Delete the content of the following files and replace it with the specified code

As show by https://www.valentinog.com/blog/react-webpack-babel/

assets/.babelrc

{
  "presets": ["@babel/preset-env", "@babel/preset-react"]
}

assets/js/app.js

import React from 'react'
import ReactDOM from 'react-dom'

const ReactOnPhoenix = () => <div>This is a React Component!!!</div>

ReactDOM.render(<ReactOnPhoenix />, document.getElementById('mountPoint'))

lib/react_on_phoenix_web/templates/page/index.html.eex

<div id="mountPoint"></div>

Change out the test assertion about what should be on the page

In this file test/react_on_phoenix_web/controllers/page_controller_test.exs

# Change it from this
"Welcome to Phoenix!"

# To this
"mountPoint"

The tests should now pass

mix test

Get back to the root directory of the app and start the server

cd ..
mix phx.server

You should now see This is a React Component!!! on the page at http://localhost:4000

You can see all the changes here https://github.com/dewetblomerus/react-on-phoenix/commit/7f31bcf6228b4656b971bfb4dd0b8762d401da2a