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

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
forEach	2382994.5 Ops/sec
map+join	1597479.8 Ops/sec
reduce	9852588.0 Ops/sec

Script Preparation code:

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

Tests:

forEach
var cssText = ""; value.forEach((fallbackValue) => { cssText += "" + normalizeDeclaration(property, fallbackValue); }); var result = cssText.slice(1);
map+join
var result = value .map((fallbackValue) => normalizeDeclaration(property, fallbackValue)) .join(";");
reduce
var result = value.reduce( (accumulator, fallbackValue) => accumulator + ";" + normalizeDeclaration(property, fallbackValue), normalizeDeclaration(property, value[0]) );