Run results for: Spread vs Object.assign (mutation)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 Edg/134.0.0.0

Browser: Chrome 134

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one month ago

Test name	Executions per second
Object.assign two objects	184918.9 Ops/sec
Spread two objects	41400.0 Ops/sec
Object.assign three objects	88899.8 Ops/sec
Spread three objects	21847.7 Ops/sec
Object.assign four objects	56413.3 Ops/sec
Spread four objects	14498.5 Ops/sec
Object.assign five objects	39123.2 Ops/sec
Spread five objects	10828.7 Ops/sec
Object.assign six objects	34141.0 Ops/sec
Spread six objects	8738.2 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};

Run results for: Spread vs Object.assign (mutation)

Object.assign two objects

Spread two objects

Object.assign three objects

Spread three objects

Object.assign four objects

Spread four objects

Object.assign five objects

Spread five objects

Object.assign six objects

Spread six objects