Note: You can insert iframes and use external CDNs however, please note that  for security reasons, you have to include all your data and CSS in the JS file or load it from URLs on https sources. E.g. use CDNs such as href="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.min.js">https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.min.js

Example