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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:96.0) Gecko/20100101 Firefox/96.0

Browser: Firefox 96

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Iteration with blank object	1150392.2 Ops/sec
Object.assign with blank object	2156827.0 Ops/sec
Iteration with created object	1090685.5 Ops/sec
Object.assign with created object	2108664.8 Ops/sec
Iteration with blank object and prototype	1018337.4 Ops/sec
Object.assign with blank object and prototype	1888993.4 Ops/sec
Iteration with blank object and prototype prop	1017088.0 Ops/sec
Object.assign with blank object and prototype prop	1894543.5 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