que-etc/resize-observer-polyfill

Health v2 · maintenance only

Adoption not part of the score

1752 stars · 130 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

A lightweight (2.44 KiB gzipped) polyfill/ponyfill for the browser Resize Observer API, implemented with MutationObserver and Mutation Events fallbacks. It lets JavaScript code observe element size changes without polling, including changes from CSS transitions, animations, and pseudo-classes.

Use cases

• observe element size changes in browsers lacking ResizeObserver support
• react to element resizing caused by CSS transitions or animations
• detect size changes from dynamic pseudo-classes like :hover
• support legacy browsers like IE9-IE11 with resize observation
• use ResizeObserver as a ponyfill without modifying the global object

When to choose

• you need ResizeObserver functionality in older browsers (IE9+, older Safari/Firefox)
• you want a tiny, spec-compliant ponyfill that avoids global object pollution
• your app must react to size changes without polling or modifying observed elements

When to avoid

• your target browsers all natively support ResizeObserver
• you need a maintained library with ongoing updates (last release Jan 2023)
• you need to observe size changes in non-DOM environments like Node.js

Facets

library · maturity maintenance

ui-components developer-tools web-development frontend browser-extensions browser cross-platform resize-observer polyfill ponyfill dom javascript mutation-observer

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