Run results for: Object.keys().length vs Map.size

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Firefox/102.0

Browser: Firefox 102

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Object.keys().length	877.3 Ops/sec
Map.size	868779100.0 Ops/sec

Script Preparation code:

var data = new Array(100000).fill(undefined).map((_,i) => i)
var obj = data.reduce((obj, idx) => {obj['idx' + idx] = idx; return obj}, {});
var map = new Map(Object.entries(obj));

Tests:

Object.keys().length
var size = Object.keys(obj).length
Map.size
var size = map.length