CSS - Position sticky

This is a delightfully nerdy exploration of how IntersectionObserver works, its quirks and caveats, and how it can be used to create a JavaScript position: sticky event as a bonus.

Here’s a secret: You may not need scroll events in your next app. Using an IntersectionObserver, I show how you can fire a custom event when position:sticky elements become fixed or when they stop sticking. All without the use of scroll listeners.

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One of the practical limitations of using CSS sticky position is that it doesn’t provide a platform signal to know when the property is active. In other words, there’s no event to know when an element becomes sticky or when it stops being sticky.