How To Add React To Phoenix 1.4

guide.md

1. cd into assets/ and install the following NPM packages:

npm i react react-dom -S
npm i @babel/preset-react -D

2. add the following line to assets/.babelrc file:

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

3. test changes:

edit lib/app_web/templates/page/index.html

<div id="root">
</div>

edit assets/js/app.js

import React from "react";
import ReactDOM from "react-dom";

const Index = () => {
  return <div>Hello React!</div>;
};

ReactDOM.render(<Index />, document.getElementById("root"));