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

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 14_5 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/87.0.4280.163 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 87

Operating system: iOS 14.5

Device Platform: Mobile

Date tested: 3 years ago

Test name	Executions per second
Control (for push)	618373.1 Ops/sec
Concat	380153.0 Ops/sec
Spread	1449420.0 Ops/sec

Script Preparation code:

window.top.tests = {control:[], concat:[], 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'); }
Spread
window.top.tests.spread.push(...window.test); if (window.top.tests.spread.length > window.cutoff) { window.top.tests.spread = []; console.log('reset spread'); }

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

Comparing the various ways to append to a large array

Control (for push)

Concat

Spread