ResizeObserver polyfill on new websites
Polyfill for the browser ResizeObserver API.
- Sites using ResizeObserver polyfill
- 28
- since Nov 2026
- Last 30 days
- 28
-
new sites, to Nov 11
none in the 30 days before - Last 7 days
- 28
-
new sites
none in the week before
| First seen | Nov 6, 2026 |
|---|---|
| Last seen | Nov 11, 2026 |
| Website | github.com |
What we found
- ResizeObserver polyfill appeared on about 28 new sites in the last 30 days.[1]
Share of new sites using ResizeObserver polyfill
The line is the 7-day average share of new sites that use ResizeObserver polyfill, since 30 October. It starts at our first detection.
Who uses ResizeObserver polyfill
| Type | Sites | Share | Bar |
|---|---|---|---|
| Developer Tools | 9 | 56.3% | |
| AI | 3 | 18.8% | |
| Content | 1 | 6.3% | |
| Education | 1 | 6.3% | |
| Finance | 1 | 6.3% | |
| Hiring & HR | 1 | 6.3% |
| Ending | Sites | Share | Bar |
|---|---|---|---|
| .com | 6 | 21.4% | |
| .org | 5 | 17.9% | |
| .dev | 4 | 14.3% | |
| .io | 3 | 10.7% | |
| .pro | 2 | 7.1% | |
| .xyz | 2 | 7.1% |
Javascript Library on new sites
| # | Movement | Tool | Share of category[2] | Bar | |
|---|---|---|---|---|---|
| 1 | – |
jQuery
|
34.1% | ||
| 2 | – | jQuery Migrate | 18.7% | ||
| 3 | – |
React Router
|
15.9% | ||
| 4 | ▼1 |
Motion
|
13.8% | ||
| 5 | ▲1 |
TanStack Router
|
11.0% | ||
| 6 | ▼1 |
Swiper
|
8.0% | ||
| 7 | ▲1 |
ES Module Shims
|
7.2% | ||
| 8 | – |
js-cookie
|
6.1% | ||
| 9 | ▼1 |
Modernizr
|
5.7% | ||
| 10 | ▲1 |
GSAP
|
4.7% | ||
| 11 | ▲1 |
Lenis
|
3.4% | ||
| 12 | ▲3 |
Three.js
|
3.2% | ||
| … | |||||
| 879 |
ResizeObserver polyfill
|
<0.1% | |||
All-time shares across the new sites we track: of all of them, and of the sites using any Javascript Library tool. All 1832 in Javascript Library
Recently launched products built on ResizeObserver polyfill
11 of the 28 sites using ResizeObserver polyfill are product launches we list individually. The other 17 are new business and personal sites: they count towards the figures above but are not listed here. A watch sends them to you.
Germany
India
France
Watches, exports and the API give you all 28 sites using ResizeObserver polyfill, from £15 a month.
Notes
- These figures cover websites that went live since April 2026, not the web as a whole.
- Some products people expect to see here are filed under a related category: UI Library.
How this page is made
FirstSited looks at each new website near the day it goes live and records what it was built with. We do not go back later, so these figures describe what sites launch with, not what they run today. A site counts towards ResizeObserver polyfill when we detect ResizeObserver polyfill on it at that look.
Every share on this page is a proportion of the new sites we were tracking at the time. Sites we found across the wider web count towards the figures, but only product launches are listed by name. How we detect technologies · How we find new sites