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

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0

Browser: Firefox 106

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Iteration with blank object	1095226.6 Ops/sec
Object.assign with blank object	1756584.6 Ops/sec
Iteration with created object	1047694.8 Ops/sec
Object.assign with created object	2771499.5 Ops/sec
Iteration with blank object and prototype	940722.9 Ops/sec
Object.assign with blank object and prototype	2159860.8 Ops/sec
Iteration with blank object and prototype prop	953002.4 Ops/sec
Object.assign with blank object and prototype prop	2196449.0 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