Run results for: Spread vs Object.assign

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Windows

Device Platform: Desktop

Date tested: 15 days ago

Test name	Executions per second
Object.assign two objects	56413.0 Ops/sec
Spread two objects	73912.7 Ops/sec
Object.assign three objects	33410.9 Ops/sec
Spread three objects	47534.8 Ops/sec
Object.assign four objects	21060.9 Ops/sec
Spread four objects	32980.9 Ops/sec
Object.assign five objects	21570.3 Ops/sec
Spread five objects	24714.4 Ops/sec
Object.assign six objects	8848.1 Ops/sec
Spread six objects	19647.5 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

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