New paste

<script>
  window.addEventListener('load',function(){
    if(window.location.pathname == "/contact-us/"){
      var set_int=setInterval(function(){

        if(jQuery('.ninja-forms-response-msg.ninja-forms-success-msg:contains("Your form has been successfully submitted.")').is(':visible')){
          gtag('event', 'submit', {
            'event_category' : 'form',
            'event_label' : 'contact'
          });
          clearInterval(set_int);
        }
      },1000)
      }

  })

</script>