Question 1

Is resize-observer-polyfill still necessary in modern browsers?

Accepted Answer

It depends on your browser support targets; for projects needing IE9-10 or older versions of Safari, yes, but for apps targeting Chrome 64+, Firefox 69+, or Edge 79+ with native ResizeObserver, you can skip it to reduce bundle size.

Question 2

How does resize-observer-polyfill compare to other polyfills like resize-observer?

Accepted Answer

This polyfill is spec-compliant and uses MutationObserver without polling, making it more performant and accurate than alternatives that rely on scroll or iframe strategies, but it has the ~20ms delay trade-off.

Question 3

How to use resize-observer-polyfill with React or Vue?

Accepted Answer

Import it as a ponyfill in component lifecycle methods; for React, use it in useEffect to observe refs, and clean up with disconnect() to avoid memory leaks, similar to native ResizeObserver integration.

Question 4

Does resize-observer-polyfill work with Internet Explorer 9?

Accepted Answer

Yes, it supports IE9 and IE10 using Mutation Events as a fallback, though with potential performance differences noted in the README's observation strategy section.

Question 5

What are the performance impacts of using this polyfill?

Accepted Answer

Minimal in most cases due to no polling, but the MutationObserver approach can slow down DOM-heavy operations by 1-3% in IE, as per the README's benchmarks, so test in target browsers.

Question 6

How to observe hover state changes with resize-observer-polyfill?

Accepted Answer

You can't directly; the README suggests adding a short CSS transition to trigger transitionend events as a workaround, which adds complexity for dynamic pseudo-classes.

resize-observer-polyfill

What is resize-observer-polyfill?

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