Run results for: Object.assign vs iteration performance, more props (Grammarly Focal)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36

Browser: Chrome 95

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Iteration with blank object	830858.0 Ops/sec
Object.assign with blank object	2314006.2 Ops/sec
Iteration with created object	649707.8 Ops/sec
Object.assign with created object	1333741.0 Ops/sec
Iteration with blank object and prototype	629457.6 Ops/sec
Object.assign with blank object and prototype	1224387.0 Ops/sec
Iteration with blank object and prototype prop	758475.1 Ops/sec
Object.assign with blank object and prototype prop	1790945.5 Ops/sec

Script Preparation code:

class Thing {
    constructor() {
        this.a1 = Math.random();
        this.a2 = Math.random();
        this.a3 = Math.random();
        this.a4 = Math.random();
        this.a5 = Math.random();
        this.a6 = Math.random();
        this.a7 = Math.random();
        this.a8 = Math.random();
        this.a9 = Math.random();
        this.aa = Math.random();
        this.ab = Math.random();
    }
}

var r = new Thing();

Tests:

Iteration with blank object
var copy = {}; for(const prop in r) copy[prop] = r[prop];
Object.assign with blank object
var copy = {}; Object.assign(copy, r);
Iteration with created object
var copy = Object.create(Object.getPrototypeOf(r)); for(const prop in r) copy[prop] = r[prop];
Object.assign with created object
var copy = Object.create(Object.getPrototypeOf(r)); Object.assign(copy, r);
Iteration with blank object and prototype
var copy = {}; Object.setPrototypeOf(copy, Object.getPrototypeOf(r)); for(const prop in r) copy[prop] = r[prop];
Object.assign with blank object and prototype
var copy = {}; Object.setPrototypeOf(copy, Object.getPrototypeOf(r)); Object.assign(copy, r);
Iteration with blank object and prototype prop
var copy = {}; copy.__proto__ = r.__proto__; for(const prop in r) copy[prop] = r[prop];
Object.assign with blank object and prototype prop
var copy = {}; copy.__proto__ = r.__proto__; Object.assign(copy, r);

Run results for: Object.assign vs iteration performance, more props (Grammarly Focal)

Iteration with blank object

Object.assign with blank object

Iteration with created object

Object.assign with created object

Iteration with blank object and prototype

Object.assign with blank object and prototype

Iteration with blank object and prototype prop

Object.assign with blank object and prototype prop