booklist javascript (jQuery) - calling google spreadsheet api, parsing response

booklist.js

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script> 
$(document).ready(function() {	
//source Google Sheets file is https://docs.google.com/spreadsheets/d/1rX4_fInsYS7vOGpnXm1UklZgvU27FXl3UYu9lx9RHHU/
$(function listBooks() {	
$.getJSON( "https://spreadsheets.google.com/feeds/list/1rX4_fInsYS7vOGpnXm1UklZgvU27FXl3UYu9lx9RHHU/1/public/full?alt=json",
  function (data) {	
    $('div#book-list').append('<ul class="items"></ul>');
    $.each(data.feed.entry, function(i,entry) {
      var item = '<span style="display:none">' + entry.id.$t + '</span>';	
      item += '<img src="https://covers.openlibrary.org/b/isbn/' + entry.gsx$isbn.$t + '-S.jpg"/>';
      item += '<span class="meta"><a href="https://www.worldcat.org/isbn/' + entry.gsx$isbn.$t + '">' + entry.title.$t + '</a>';	
      item += '<br/>Author: ' + entry.gsx$author.$t;	
      if (entry.gsx$notes.$t) {	
        item += '<br/>Description: ' + entry.gsx$notes.$t;	
      }	
      $('.items').append('<li>' + item + '</span></li>');	
    });
  });
});
});
</script>

I'm not sure you would be able to use a non-public spreadsheet as the functions rely on generated RSS/ATOM feeds from a published sheet. More information about the Google Spreadsheet API can be found at https://developers.google.com/google-apps/spreadsheets/ but from what I'm reading there you will need to 'publish to web' to make this work. Good luck!