The ResizeObserver API provides a highly efficient and non-blocking way to observe size changes on any DOM element, not just the browser window. This collection demonstrates how to use this API to create truly component-level responsiveness (Container Queries), where elements react to the size of their parent. You’ll see how its asynchronous nature eliminates performance bottlenecks associated with frequent window.onresize event listeners and forced layout recalculations.
This is a Container-Aware Plotly Chart. It forces a data visualization component to respond strictly to its parent element’s dimensions rather than the global window size. Its function is to prevent layout breakages in complex dashboards where sidebars toggle or CSS Grid tracks resize dynamically without triggering a global window resize event. (Requires: plotly-js)
Chrome 64+
Edge 79+
Firefox 69+
Safari 13.1+See the Pen Container-Aware Plotly Chart.
This is a Staggered Text Scroll Reveal. It parses structural typography into independent animated lines. Its function is to pace the reader’s attention, transforming static paragraphs into dynamic narrative elements triggered by viewport intersection. (Requires: gsap-js, scroll-trigger-js, lenis-js, split-type)
Chrome 64+
Edge 79+
Firefox 69+
Safari 13.1+See the Pen Staggered Text Scroll Reveal.
This is a Matcap Instanced Disco Geometry demo. It renders multiple unique 3D geometries (Torus Knot, Icosahedron, Torus) using the WebGL Instanced Mesh technique. Instead of drawing individual planes for every mirror on the surface of the shape, it creates one InstancedMesh per object, mathematically orienting thousands of tiny reflective mirrors to mimic a faceted, crystal-like disco surface. (Requires: Three.js)
Chrome 60+
Edge 79+
Firefox 55+
Safari 11+See the Pen Matcap Instanced Disco Geometry.
This Interactive Neon Grid Trail creates a sleek, cybernetic atmosphere ideal for tech portfolios or futuristic landing pages. It utilizes the HTML5 Canvas API to render a grid of invisible squares that light up in neon teal upon interaction. The effect features a “memory” mechanic where the illuminated cells hold their charge for a moment before gracefully fading back into the darkness, creating a satisfying trail behind the user’s cursor.
Chrome 4+
Edge 12+
Firefox 3.6+
Safari 4+See the Pen Interactive Neon Grid Trail.
This Smart CSS Anchored Selection Pills component demonstrates the bleeding edge of CSS layout capabilities. It uses the new CSS Anchor Positioning API to tether a visual “pill” indicator to the currently selected radio button without JavaScript calculations for position. The demo includes a robust fallback system that calculates positions via ResizeObserver for browsers that don’t yet support anchors, ensuring a consistent experience across the board. It also features advanced masking techniques (SVG and CSS Filters) to create “knockout” text effects where the selected text changes color inversely to the pill background. (Requires: GSAP, Tweakpane)
Chrome 125+
Edge 125+
Safari 26+
Firefox 147+See the Pen Smart CSS Anchored Selection Pills.
This WebGL Fluid Smoke Button elevates standard UI interactions by embedding a real-time generative shader directly into the interface. Instead of using a heavy video file, it calculates complex fluid dynamics on the fly using Fractional Brownian Motion (fBM). The result is a mesmerizing, never-repeating smoky background that reacts to hover states with a smooth scale and rotation effect, styled effortlessly via Tailwind CSS. (Requires: fragment-canvas, Tailwind CSS)
Chrome 90+
Edge 90+
Firefox 90+
Safari 15+See the Pen WebGL Fluid Smoke Button.
A demonstration of advanced synchronization between the ResizeObserver API and the Popover API, where the Observer monitors the notification’s size change to automatically dismiss it once the height hits zero. It uses @starting-style and transition to create a smooth and controlled fade-out effect for the popover element.
Features a smooth article reading progress indicator built with React Hooks and ResizeObserver, with scroll handling optimized using passive event listeners for superior performance.
A demonstration of high-performance font size auto-fitting to container width using ResizeObserver and CSS variables, ensuring smooth scaling of h1 headings while preventing layout thrashing via requestAnimationFrame.
See the Pen Fit Text to Container using ResizeObserver.
Efficient Container-Aware image loading with ResizeObserver and optimized candidate selection (DPI awareness, size tolerance, aspect ratio matching), actively preventing the download of unnecessarily large image files.
See the Pen Web Component for Container Aware Image Loading.
