Run results for: Object.entries VS Object.keys.map

Run details:

User agent: Mozilla/5.0 (Mobile; LYF/F120B/LYF-F120B-001-02-34-170919-i;Android; rv:48.0) Gecko/48.0 Firefox/48.0 KAIOS/2.5

Browser: Firefox Mobile 48

Operating system: Firefox OS

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
Object.entries	1676.7 Ops/sec
Object.keys.map	395.9 Ops/sec

Script Preparation code:

function makeid() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 5; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return text;
}

window.parentObj = {};

for (let i = 0; i < 100; i++) {
	window.parentObj[makeid()] = makeid();
}

Tests:

Object.entries
const newObj = {}; Object.entries(window.parentObj).forEach(([k, v], i) => { if ((i % 2) === 0) { newObj[k] = v; } });
Object.keys.map
const newObj = {}; Object.keys(window.parentObj).map(key => [key, window.parentObj[key]]).forEach(([k, v], i) => { if ((i % 2) === 0) { newObj[k] = v; } });