Run results for: SetProperty vs CSSStyleSheet

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.3 Safari/605.1.15

Browser: Safari 17

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
SetProperty	1.5 Ops/sec
CSSStyleSheet	5572.3 Ops/sec

Script Preparation code:

count = 10000;
names = new Array(count).fill(0).map((_, index) => "--foobar-" + index);

Tests:

SetProperty
names.forEach(name => document.body.style.setProperty(name, "12px"));
CSSStyleSheet
const sheet = new CSSStyleSheet; const data = names.reduce((name, accum) => {accum += name + ": 12px;"}, ""); sheet.replaceSync(":root {" + data + "}"); document.addoptedStyleSheets = [sheet]