onosendi/index.html

## index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <title>Foo</title>
  </head>
  <body>
    <div id="root" data-foo="{&quot;foo&quot;: &quot;bar&quot;}"></div>
  </body>
</html>

## index.js
import React from 'react';
import ReactDOM from 'react-dom';

const rootEl = document.getElementById('root');

let foo;
try {
  foo = JSON.parse(rootEl.dataset.foo);
} catch (error) {
  console.error(error);
}

function App({ foo }) {
  console.log(foo);

  return null;
}

ReactDOM.render(<App foo={foo} />, rootEl);
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="utf-8" />
	<title>Foo</title>
	</head>
	<body>
	<div id="root" data-foo="{"foo": "bar"}"></div>
	</body>
	</html>
	import React from 'react';
	import ReactDOM from 'react-dom';

	const rootEl = document.getElementById('root');

	let foo;
	try {
	foo = JSON.parse(rootEl.dataset.foo);
	} catch (error) {
	console.error(error);
	}

	function App({ foo }) {
	console.log(foo);

	return null;
	}

	ReactDOM.render(<App foo={foo} />, rootEl);