Google recaptcha

window.onload = function() { 
    var $recaptcha = document.querySelector('#g-recaptcha-response'); 
 
    if($recaptcha) { 
        $recaptcha.setAttribute("required", "required"); 
    } 
  const $form = document.querySelector('form'); 
  $form.addEventListener('submit', (event) => { 
    event.preventDefault(); 
    console.log('prevented submit by code for demo'); 
  }); 
};

.wrapper { 
  padding: 100px; 
} 
 
#g-recaptcha-response { 
    display: block !important; 
    position: absolute; 
    margin: -78px 0 0 0 !important; 
    width: 302px !important; 
    height: 76px !important; 
    z-index: -999999; 
    opacity: 0; 
}

<div class="wrapper"> 
  <form> 
     <div class="g-recaptcha" data-sitekey="6LcCsWoUAAAAAO520lKAXtblM0p76KNXL3n0dVUZ"></div> 
    <button type="submit"> Submit</button> 
  </form> 
</div>