Run results for: Array spread operator vs push in reduce

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 13_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/85.0.4183.92 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 85

Operating system: iOS 13.3

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
spread operator	1892158.0 Ops/sec
Push	2039500.0 Ops/sec

Tests:

spread operator
var arr = [ { "opportunityId": 5943111, "findingList": [ { "findingId": 6919 } ], }, { "opportunityId": 5943111, "findingList": [ { "findingId": 6918, "findingId": 6917 } ] } ] arr.reduce((acc, findingInOpp) => [...acc, ...findingInOpp.findingList.map(({ findingId }) => findingId)],[])
Push
var arr = [ { "opportunityId": 5943111, "findingList": [ { "findingId": 6919 } ], }, { "opportunityId": 5943111, "findingList": [ { "findingId": 6918, "findingId": 6917 } ] } ] arr.reduce((acc, findingInOpp) => { acc.push(...findingInOpp.findingList.map(({ findingId }) => findingId)) return acc },[])

Run results for: Array spread operator vs push in reduce

Compare the new ES6 spread operator with push inside reduce

spread operator

Push