Run results for: array push vs reduce

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.0) Gecko/20100101 Firefox/137.0

Browser: Firefox 137

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

optimized reduce

12.8M/s

optimized push

12.7M/s

array push

8.9M/s

reduce

8.1M/s

View exact numbers

Test name	Executions per second
✓ optimized reduce	12,808,278 Ops/sec
optimized push	12,721,282 Ops/sec
array push	8,867,529 Ops/sec
reduce	8,143,050 Ops/sec

Script Preparation code:

var oldData = { item1: 'olditem1', item2: 'olditem2', item3: 'unchanged' };
var newData = { item1: 'newitem1', item3: 'unchanged', item4: 'something else' };

Tests:

array push
const result = []; Object.entries(oldData).forEach(([key, oldValue]) => { const newValue = newData[key]; if (typeof newValue === 'undefined' || oldValue !== newValue) { result.push(key); } });
optimized push
const result = []; Object.keys(oldData).forEach((key) => { if (oldData[key] !== newData[key]) { result.push(key); } });
reduce
const result = Object.entries(oldData).reduce((accum, [key, oldValue]) => { const newValue = newData[key]; if (typeof newValue === 'undefined' || oldValue !== newValue) { return [...accum, key]; } return accum; }, []);
optimized reduce
const result = Object.keys(oldData).reduce((accum, key) => { if (oldData[key] !== newData[key]) { accum.push(key); } return accum; }, []);