During the presentation, Fred demonstrates dynamically loading JS using “Islands Architecture”,a strategy where small HTML placeholders are progressively upgraded with dynamic or interactive content as-needed.
The demonstration involves waiting on the viewport visibility of a div placeholder before loading some JS.
Using an IIFE an
IntersectionObserver is attached to keep an eye on a preceding a DOM Node. Once in view it’ll disconnect the
IntersectionObserver and run whatever JS you want it to run (such as loading and rendering a React App).