Run results for: Dynamic property assignment vs Object.assign

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Direct assignment	18269.8 Ops/sec
Object.assign	335.0 Ops/sec

Script Preparation code:

var listOfNumbers = Array(10000).fill().reduce((acc, x, i) => (acc.push(i), acc), []);

Tests:

Direct assignment
var a = listOfNumbers.reduce((acc, x) => { acc[x] = x * 2; return acc; }, {});
Object.assign
var b = listOfNumbers.reduce((acc, x) => Object.assign(acc, { [x]: x * 2 }), {});