This content originally appeared on DEV Community and was authored by Muhammad Ibtisam

Today I Learned: Intersection Observer API in JavaScript

As a developer, I’m always looking for ways to improve performance and user experience — and today I explored something incredibly useful: the Intersection Observer API.

Why It’s Awesome

Instead of relying on expensive scroll event listeners, the Intersection Observer API provides a modern, efficient way to detect when an element enters or exits the viewport.

Use Cases:

• Lazy-loading images
• Triggering animations on scroll
• Infinite scroll implementations
• Tracking element visibility for analytics

It’s clean, lightweight, and extremely helpful for modern web apps and SPAs.

Live Demo (Scroll Animation)

I created a quick example that triggers animations when elements come into view, using Intersection Observer and Tailwind CSS.

Watch the Loom video demo

GitHub Code

If you’d like to check out the code or try it yourself, here’s the repo:

GitHub Repository – JS_Intersection_Observer_API

Let’s Talk!

Have you used the Intersection Observer API in your projects?

Any interesting tricks, animations, or use cases?

Drop your thoughts in the comments — I’d love to learn from your experience!

This content originally appeared on DEV Community and was authored by Muhammad Ibtisam