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

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/115.1 Mobile/15E148 Safari/605.1.15

Browser: Mobile Safari 16

Operating system: iOS 16.6

Device Platform: Mobile

Date tested: 9 months ago

Test name	Executions per second
Iteration with blank object	1914488.0 Ops/sec
Object.assign with blank object	4250251.0 Ops/sec
Iteration with created object	1468575.0 Ops/sec
Object.assign with created object	2563194.0 Ops/sec
Iteration with blank object and prototype	727823.4 Ops/sec
Object.assign with blank object and prototype	862485.8 Ops/sec
Iteration with blank object and prototype prop	612203.0 Ops/sec
Object.assign with blank object and prototype prop	664623.3 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