Run results for: Concat vs push(...) vs spread for large arrays

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148 LightSpeed [FBAN/MessengerLiteForiOS;FBAV/369.0.0.11.107;FBBV/381862875;FBDV/iPhone12,1;FBMD/iPhone;FBSN/iOS;FBSV/15.6;FBSS/2;FBCR/;FBID/phone;FBLC/da;FBOP/0]

Browser: Mobile Safari 15

Operating system: iOS 15.6

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
Control (for push)	485465.8 Ops/sec
Concat	313172.9 Ops/sec
Push (with spread)	1323005.1 Ops/sec
Spread	118502.6 Ops/sec

Script Preparation code:

window.top.tests = {control:[], concat:[], pushSpread: [], spread:[]};
window.test = (new Array(10)).fill(null);
window.cutoff = 5000;

Tests:

Control (for push)
for (let element of window.test) window.top.tests.control.push(element); if (window.top.tests.control.length > window.cutoff) { window.top.tests.control = []; console.log('reset control'); }
Concat
window.top.tests.concat = window.top.tests.concat.concat(window.test); if (window.top.tests.concat.length > window.cutoff) { window.top.tests.concat = []; console.log('reset concat'); }
Push (with spread)
window.top.tests.pushSpread.push(...window.test); if (window.top.tests.pushSpread.length > window.cutoff) { window.top.tests.pushSpread = []; console.log('reset push spread'); }
Spread
window.top.tests.spread = [...window.top.tests.spread, ...window.test]; if (window.top.tests.spread.length > window.cutoff) { window.top.tests.spread = []; console.log('reset spread'); }

Run results for: Concat vs push(...) vs spread for large arrays

Comparing the various ways to append to a large array

Control (for push)

Concat

Push (with spread)

Spread