chatbot-facebook

  window.fbAsyncInit = function() {
      FB.init({
        xfbml            : true,
        version          : 'v3.3'
      });
    };
  
    (function(d, s, id) {
    var js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return;
    js = d.createElement(s); js.id = id;
    js.src = 'https://connect.facebook.net/en_US/sdk/xfbml.customerchat.js';
    fjs.parentNode.insertBefore(js, fjs);
  }(document, 'script', 'facebook-jssdk'));