Run results for: spread operator vs array.concat()

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36

Browser: Chrome 117

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
spread big	77051.9 Ops/sec
concat big	904454.1 Ops/sec
spread small	7429549.5 Ops/sec
concat small	5061170.5 Ops/sec
spread big smal	1125350.8 Ops/sec
spread small big	92800.5 Ops/sec
concat big small	2105375.2 Ops/sec
concat small big	1256182.9 Ops/sec
shallow copy spread	1884293.4 Ops/sec
shallow copy concat	1908846.6 Ops/sec

Script Preparation code:

var a = Array.from({length: 1000}).map((_, i)=>`${i}`);
var b = Array.from({length: 2000}).map((_, i)=>`${i}`);
var aSmall = ['a', 'b', 'c', 'd'];
var bSmall = ['e', 'f', 'g', 'h', 'i'];

Tests:

spread big
const c = [...a, ...b];
concat big
const c = a.concat(b);
spread small
const c = [...aSmall, ...bSmall];
concat small
const c = aSmall.concat(bSmall);
spread big smal
const c = [...a, ...bSmall];
spread small big
const c = [...aSmall, ...b];
concat big small
const c = a.concat(bSmall);
concat small big
const c = aSmall.concat(b);
shallow copy spread
const c = [...b];
shallow copy concat
const c = [].concat(b);

Run results for: spread operator vs array.concat()

spread big

concat big

spread small

concat small

spread big smal

spread small big

concat big small

concat small big

shallow copy spread

shallow copy concat