在本地检查reCaptcha验证

Does anyone know of a way to locally verify when a google reCaptcha has been completed? I want to submit the form automatically when the the user has finished with the captcha - using the completion of the captcha as a sort of submit button.

<div class="g-recaptcha" data-sitekey="KEY"></div>
<button name='submitting' value='sub'>Submit</button></br></div>

Figured it out,

<script>function submitCap() { alert('Captcha Completed'); }</script>
<div class="g-recaptcha" data-callback='submitCap' data-sitekey="KEY"></div>