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) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser: Chrome 120

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Object.assign with blank object

2.3M/s

Object.assign with blank object and prototype prop

1.6M/s

Object.assign with created object

1.3M/s

Object.assign with blank object and prototype

1.2M/s

Iteration with blank object

857K/s

Iteration with blank object and prototype prop

725K/s

Iteration with created object

663K/s

Iteration with blank object and prototype

640K/s

View exact numbers

Test name	Executions per second
✓ Object.assign with blank object	2,311,630 Ops/sec
Object.assign with blank object and prototype prop	1,597,628 Ops/sec
Object.assign with created object	1,338,702 Ops/sec
Object.assign with blank object and prototype	1,236,175 Ops/sec
Iteration with blank object	857,258 Ops/sec
Iteration with blank object and prototype prop	724,508 Ops/sec
Iteration with created object	662,647 Ops/sec
Iteration with blank object and prototype	639,820 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);