var el = document.createElement("script");
el.async = true;
el.defer = true;
el.src = "https://cdn.jsdelivr.net/npm/[email protected]${version}/dist/oneaccount.min.js";
document.body.appendChild(el);

<script defer async src="https://cdn.jsdelivr.net/npm/[email protected]<version>/dist/oneaccount.min.js"></script>

if (window.oneaccount) {
  initOneaccount();
} else {
  document.addEventListener("oneaccount-loaded", initOneaccount);
}
​
// init the library
function initOneaccount() {
  window.oneaccount.init("your external id", {
    // NOTE: Please check the Library options page for more customisations
    iOSRedirectURL: "/user", // required
    callbackURL: "/oneaccountauth", // required
  });
}

<!-- NOTE: the classes are important for the library to attach the click bindings -->
<button class="oneaccount-button oneaccount-show">Sign in/up using One account</button>

document.addEventListener("oneaccount-authenticated", function(event) {
  // data contains any data you have returned from the backend
  var data = event.detail;
  // your business logic here
});

<?php declare(strict_types=1);
​
namespace App\Http\Controllers;
​
use App\Http\Controllers\Controller;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Oilastudio\Oneaccount\FileEngine;
use Oilastudio\Oneaccount\Oneaccount;
use Illuminate\Support\Facades\Redis;
​
final class RedisEngine implements EngineInterface
{
	public function set(string $key, array $value): bool
	{
		Redis::set($key, json_encode($value), 'EX', 3 * 60);
	}
​
	public function get(string $key): array
	{
		$data = json_decode(Redis::get($key));
		Redis::del($key);
		return $data;
	}
}
​
​
class OneaccountController extends Controller
{
	// The route URL is the callback URL you have set when you created One account app.
	public function oneaccountauth(Request $request)
	{
		// provide an implementation of EngineInterface for example redis:
		$oneaccount = new Oneaccount(new RedisEngine());
		// you can implement the interface using any DB or cache.
		// for development purposes you can use file engine implementation 
		// (creates files in your file system, make sure to delete them):
		// $oneaccount = new Oneaccount(new FileEngine());
		$user = $oneaccount->auth();
​
		// NOTE: never return code 200 if a user is not authenticated
		if (false !== $user) {
			return new JsonResponse(['success' => false], 401);
		}
​
		// since One account doesn't differentiate between sign up and sign in, 
	  // you can use userId to check if the user signed up c on your website or not.
	  // the same way you can access any other data you requested from the user:
​
		// $userId = $user['userId'];
		// $email = $user['email'];
		$firstName = $user['firstName'];
		return new JsonResponse(['firstName' => $firstName]);        
	}
}