example/html/v2/explicitly.html

<html>

<head>
  <title>reCAPTCHA demo: Explicit render after an onload callback</title>
</head>

<body>
  <h3>
    <a href="https://developers.google.com/recaptcha/docs/display#explicitly_render_the_recaptcha_widget">
      Explicitly render the reCAPTCHA widget
    </a>
  </h3>
  <form action="/signin" method="POST">
    <div id="html_element"></div>
    <br>
    <input type="submit" value="Submit">
  </form>
  <script src="https://www.google.com/recaptcha/api.js?onload=onloadCallback&render=explicit" async defer>
  </script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"
    integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
  <script type="text/javascript">
    var onloadCallback = function () {
      grecaptcha.render('html_element', {
        'sitekey': 'your_site_key'
      });
    };
  </script>
</body>

</html>