Run results for: Spread vs Object.assign

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:137.0) Gecko/20100101 Firefox/137.0

Browser: Firefox 137

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Object.assign two objects

652K/s

Object.assign three objects

334K/s

Spread two objects

309K/s

Object.assign four objects

215K/s

Spread three objects

185K/s

Object.assign five objects

131K/s

Spread four objects

127K/s

Object.assign six objects

101K/s

Spread five objects

97K/s

Spread six objects

76K/s

View exact numbers

Test name	Executions per second
✓ Object.assign two objects	651,570 Ops/sec
Object.assign three objects	334,371 Ops/sec
Spread two objects	309,407 Ops/sec
Object.assign four objects	215,214 Ops/sec
Spread three objects	185,386 Ops/sec
Object.assign five objects	131,307 Ops/sec
Spread four objects	126,941 Ops/sec
Object.assign six objects	100,664 Ops/sec
Spread five objects	96,622 Ops/sec
Spread six objects	76,463 Ops/sec

Script Preparation code:

window.object1 = {};
window.object2 = {};
window.object3 = {};
window.object4 = {};
window.object5 = {};
window.object6 = {};

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;
};

function populate(object) {
  for (let i = 0; i < 100; i++) {
    object[makeid()] = makeid();
  }
};

populate(object1);
populate(object2);
populate(object3);
populate(object4);
populate(object5);
populate(object6);

Tests:

Object.assign two objects
const object7 = Object.assign({}, object1, object2);
Spread two objects
const object7 = {...object1, ...object2};
Object.assign three objects
const object7 = Object.assign({}, object1, object2, object3);
Spread three objects
const object7 = {...object1, ...object2, ...object3};
Object.assign four objects
const object7 = Object.assign({}, object1, object2, object3, object4);
Spread four objects
const object7 = {...object1, ...object2, ...object3, ...object4};
Object.assign five objects
const object7 = Object.assign({}, object1, object2, object3, object4, object5);
Spread five objects
const object7 = {...object1, ...object2, ...object3, ...object4, ...object5};
Object.assign six objects
const object7 = Object.assign({}, object1, object2, object3, object4, object5, object6);
Spread six objects
const object7 = {...object1, ...object2, ...object3, ...object4, ...object5, ...object6};