Run results for: String accumulation with forEach vs. map+join

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:79.0) Gecko/20100101 Firefox/79.0

Browser: Firefox 79

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
map+join	1281953.0 Ops/sec
forEach	2182397.5 Ops/sec

Script Preparation code:

var property = "justify-content";
var value = ["space-around", "space-evenly"];

function normalizeDeclaration(property, value) {
	return property + ":" + value;
}

Tests:

map+join
var result = value .map((fallbackValue) => normalizeDeclaration(property, fallbackValue)) .join(";");
forEach
var cssText = ""; value.forEach((fallbackValue) => { cssText += "" + normalizeDeclaration(property, fallbackValue); }); var result = cssText.slice(1);