Facebook SDK Javascript

HTML

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>SocialAuth</title>
    <link rel="stylesheet" href="https://bootswatch.com/4/cerulean/bootstrap.css">
    <style media="screen">
      #fb-btn{margin-top:20px;}
      #profile, #logout, #feed{display:none}
    </style>
  </head>
  <body>
    <script>
      window.fbAsyncInit = function() {
        FB.init({
          appId      : 'YOURAPPID',
          cookie     : true,
          xfbml      : true,
          version    : 'v2.8'
        });

        FB.getLoginStatus(function(response) {
            statusChangeCallback(response);
        });
      };

      (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 = "//connect.facebook.net/en_US/sdk.js";
         fjs.parentNode.insertBefore(js, fjs);
       }(document, 'script', 'facebook-jssdk'));

       function statusChangeCallback(response){
         if(response.status === 'connected'){
           console.log('Logged in and authenticated');
           setElements(true);
           testAPI();
         } else {
           console.log('Not authenticated');
           setElements(false);
         }
       }

      function checkLoginState() {
        FB.getLoginStatus(function(response) {
          statusChangeCallback(response);
        });
      }

      function testAPI(){
        FB.api('/me?fields=name,email,birthday,location', function(response){
          if(response && !response.error){
            //console.log(response);
            buildProfile(response);
          }

          FB.api('/me/feed', function(response){
            if(response && !response.error){
              buildFeed(response);
            }
          });
        })
      }

      function buildProfile(user){
        let profile = `
          <h3>${user.name}</h3>
          <ul class="list-group">
            <li class="list-group-item">User...