Capture Post Content in a Gravity Form Field

Optionally @replace .entry-content, <!-- START CONTRACT -->, <!-- END CONTRACT -->

// Send all HTML content between contentStart and contentEnd comments into Gravity Form paragraph text field with class of `content_receiver`
<script>
   jQuery(document).ready(function(){
      const contentStart = '<!-- START CONTRACT -->';
      const contentEnd = '<!-- END CONTRACT -->';
      const contentFull = jQuery('.entry-content').html();
      const contentSent = contentFull.substr(0,contentFull.indexOf(contentEnd)).substr(contentFull.indexOf(contentStart)).replace(contentStart,'');
      jQuery('.content_receiver textarea').val(contentSent.replace(/\n/gm,' '));
   });
</script>

Source