Run results for: Object.defineProperties vs individual Object.defineProperty calls

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:98.0) Gecko/20100101 Firefox/98.0

Browser: Firefox 98

Operating system: Ubuntu

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Bulk definition	312.3 Ops/sec
Individual definition	834.7 Ops/sec
Simple assignment	811.1 Ops/sec

Script Preparation code:

obj = {};
let targets = [obj];
for (let levels = 0; levels < 2; levels++) {
  for (let i = 1; i <= 10; i++)
    targets.forEach(tgt => tgt[i] = {});
  targets = targets.flatMap(tgt => Object.keys(tgt).map(key => tgt[key]));
}

Tests:

Bulk definition
function _copy(data) { const other = {}; const descs = Object.getOwnPropertyDescriptors(data); for (let prop in descs) { let desc = descs[prop]; desc.value = _copy(desc.value); } Object.defineProperties(other, descs) } _copy(obj);
Individual definition
function _copy(data) { const descs = Object.getOwnPropertyDescriptors(data); const other = {}; for (let prop in descs) { let desc = descs[prop]; desc.value = _copy(desc.value); Object.defineProperty(other, prop, desc); } } _copy(obj);
Simple assignment
function _copy(data) { const descs = Object.getOwnPropertyDescriptors(data); const other = {}; for (let prop in descs) { let desc = descs[prop]; desc.value = _copy(desc.value); other[prop] = desc.value; } } _copy(obj)

Run results for: Object.defineProperties vs individual Object.defineProperty calls

Bulk definition

Individual definition

Simple assignment