Javascript Event Listener

<script src="https://d3pw37i36t41cq.cloudfront.net/embed_v2.js" async></script>
<script>
  window._wf = window._wf || [];
_wf.push({ id: '3xz1oVMRvKB96hhhjjhh', onReady: function(api) {
    api.onSubmit(function(data) {
      console.log('onSubmit', data);
    });

    api.onLeadSubmit(function(data) {
      console.log('onLeadSubmit', data);
    });
  }});
</script>

In response (data variable in this example) we have the following fields: 

email 

first_name 

last_name 

phone 

custom_fields - this is object with nested custom fields: for example it will contain: Agreement: true, quiz1: "option4", secondary_phone: "123123123"