Run results for: Array splice vs object assign

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.4 Mobile/15E148 DuckDuckGo/7 Safari/605.1.15

Browser: Mobile Safari 15

Operating system: iOS 15.4

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
Array splice	335283.5 Ops/sec
ES6 Object Spread	61.7 Ops/sec
Object property assign	10057830.0 Ops/sec

Script Preparation code:

var input = [];
for (var i = 0; i < 50000; i++) {
    input.push({
        id: i,
        data: 'something'
    })
}

Tests:

Array splice
const index = input.findIndex(val => val.id === 999); input.splice(index, 1, {id: 999, data: 'somethingElse'});
ES6 Object Spread
input = { ...input, [999]: {id: 999, data: 'somethingElse'} }
Object property assign
input[999] = {id: 999, data: 'somethingElse'}

Run results for: Array splice vs object assign

Array splice

ES6 Object Spread

Object property assign