WeakMap polyfill on new websites

1. WeakMap polyfill appeared on about 41 new sites in the last 30 days.^[1]
2. Almost all new WeakMap polyfill sites also use Vimeo.

Each bar counts the new sites we found using WeakMap polyfill in one week, since 14 September. The chart starts at our first detection. Paler bars cover only part of a week.

#	Movement	Tool	Share of all sites	Share of category[3]	Bar
1	–	jQuery	13.7%	34.1%
2	–	jQuery Migrate	7.5%	18.7%
3	–	React Router	6.4%	15.9%
4	▼1	Motion	5.6%	13.8%
5	▲1	TanStack Router	4.4%	11.0%
6	▼1	Swiper	3.2%	8.0%
7	▲1	ES Module Shims	2.9%	7.2%
8	–	js-cookie	2.5%	6.1%
9	▼1	Modernizr	2.3%	5.7%
10	▲1	GSAP	1.9%	4.7%
11	▲1	Lenis	1.4%	3.4%
12	▲3	Three.js	1.3%	3.2%
…
739	▲343	WeakMap polyfill	<0.1%	<0.1%

All-time shares across the new sites we track: of all of them, and of the sites using any Javascript Library tool. Among October launches it ranked #1020 in Javascript Library, up from #1363 in September. All 1832 in Javascript Library

Tool	Sites with both	vs all new sites	Bar
Vimeo	42	102x

Tools that turn up far more often on WeakMap polyfill sites than on new sites in general, and how many times as common each one is there.

3 of the 42 sites using WeakMap polyfill are product launches we list individually. The other 39 are new business and personal sites: they count towards the figures above but are not listed here. A watch sends them to you.

• EKuore Digital Veterinary Stethoscope dvmcentral.com
• datasets.store datasets.store
• 80degrees — Vibe Code Real, Market-Ready Products on Your PC 80degreeslabs.com

Site	Found	Also detected
EKuore Digital Veterinary Stethoscope dvmcentral.com · Health	Nov 7
datasets.store datasets.store · Developer Tools · Ukraine	Nov 7
80degrees — Vibe Code Real, Market-Ready Products on Your PC 80degreeslabs.com	Oct 27

Watches, exports and the API give you all 42 sites using WeakMap polyfill, from £15 a month.

1. These figures cover websites that went live since April 2026, not the web as a whole.
2. Country comes from what each site says about itself, such as a company registration, legal terms or a phone number, not just its domain ending. Too few sites state their country plainly for the usual count, so this one also counts single signals: a country domain ending, a phone number (for North America, its area code), a location the site declares in its own page metadata, or a country-specific vendor stack and the page language where they agree and nothing contradicts them. Read these as likely rather than certain.
3. Some products people expect to see here are filed under a related category: UI Library.