Integrating Drupal and Non-Drupal Site Content I'm on a project to build some interactive data visualizations in D3. At no time during the discussion phase with the client did they mention the site had to be in Drupal.

We've now developed a draft site, and my team builds sites with just HTML, CSS and JavaScript, and no one has experience with Drupal. I know it's technically possible to implement what we've done in Drupal, but way beyond the scope of what was agreed upon.

The client seems open to having a launch page in Drupal that goes to the non-Drupal site with the fancy data viz stuff, but I'm not really sure how to go about this. Any recommendations?

All I can think of right now is just to have bunch of links back and forth between the two platforms, but seems kludgy.
Hard to say from your post if there is any real content management involved here, but if so - if Drupal is a requirement and your expertise is in JS - maybe look at a decoupled approach?

... in Headless Drupal, the visitor will see pages created with Javascript frameworks such as Angular.js or Backbone.js. They will not see a traditional Drupal theme. That's where the &quot;Headless&quot; name comes from: Drupal's head / theme is missing.
In this situation, Drupal is mainly used as store for data that is then read by the framework. The normal Drupal interface is still used by users to enter the content that will appear on the website.

Source: What is Headless Drupal? (OSTraining)