Progressive Enhancement inside of JavaScript

Lately I've had the opportunity to travel by train and coach, during which time I also tend to work. It's really only during these periods that I'm reminded of how web sites fail so terribly over a slow connection. On the odd occasion I can be guilty of this too. I had a tiny tool that takes markdown and renders it for quick reading (no apps, or split view in VS Code, etc). When I loaded it up on the train, the page asked me to drop the file in to be rendered, which I dutifully did, only for the page to load the source markdown. It's nothing new, but Progressive Enhancement doesn't only apply to HTML being enhanced with JavaScript. It also applies within JavaScript. Sometimes this was the cut the mustard test, but sometimes it's about thinking laterally about JavaScript. In particular, can I capture the user's intent if they try to interact with my page before it's fully ready? Below I've made a visual demonstration of the issue, and the effect after I fixed the logic. It shows the…