Install build of create-react-app into WordPress template

// index.js – don't let registerServiceWorker run in WP environment

if (process.env.NODE_ENV !== 'production') {
  registerServiceWorker()
}




// functions.php

function install_react_app($app_dir = 'react-app') {

	$directory = get_template_directory_uri() . '/' . $app_dir;

	$manifest = json_decode(file_get_contents($directory . '/build/asset-manifest.json'), true);
	
	if(isset($manifest['main.css'])) {
		wp_enqueue_style( 'react-app-css', $directory . '/build/' . $manifest['main.css'] );
	}

	echo isset($manifest['main.js']);
	
	if(isset($manifest['main.js'])) {
		wp_register_script( 'react-app-js', $directory . '/build/' . $manifest['main.js'], array(), false, true );
		wp_enqueue_script( 'react-app-js' );
	}

}

function my_scripts () {
	install_react_app();
}

add_action( 'wp_enqueue_scripts', 'my_scripts' );





// template.php
<?php
/**
 * Template Name: Template 
 */

get_header(); ?>

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

<?php get_footer();