Benchmark: Shallow cloning an object: Object.assign() vs. Spread vs. for-in loop

Script Preparation code:

var orig = {
    hey: "howdy"
}
for (i = 0; i < 1000; i++) {
    orig[Math.random() + ""] = i % 3 === 0 ? "some string blah blah blah" : i % 3 === 1 ? ["a", "b", "c"] : {
        yo: "hello"
    };
}
var hasOwnProperty = Object.prototype.hasOwnProperty;

Tests:

Object.assign()
const clone = Object.assign({}, orig, { hey: "sup" }) clone.hey
Spread
const clone = { ...orig, hey: "sup" } clone.hey
For-in (no hasOwnProperty check)
const clone = {}; for (const k in orig) { clone[k] = orig[k] } clone.hey = "sup" clone.hey
For-in (direct hasOwnProperty check)
const clone = {}; for (const k in orig) { if (orig.hasOwnProperty(k)) { clone[k] = orig[k] } } clone.hey = "sup" clone.hey
For-in (indirect hasOwnProperty check)
const clone = {}; for (const k in orig) { if (hasOwnProperty.call(orig, k)) { clone[k] = orig[k] } } clone.hey = "sup" clone.hey

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign()
Spread
For-in (no hasOwnProperty check)
For-in (direct hasOwnProperty check)
For-in (indirect hasOwnProperty check)

Fastest: N/A

Slowest: N/A

ⓘ Get performance results from real users on your website with Request Metrics.

Website Performance Monitoring by Request Metrics

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (X11; CrOS x86_64 13505.63.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Browser/OS: Chrome 87 on Chrome OS 13505.63.0

View result in a separate tab

Test name	Executions per second
Object.assign()	908.7 Ops/sec
Spread	609.3 Ops/sec
For-in (no hasOwnProperty check)	821.5 Ops/sec
For-in (direct hasOwnProperty check)	647.1 Ops/sec
For-in (indirect hasOwnProperty check)	566.9 Ops/sec

Shallow cloning an object: Object.assign() vs. Spread vs. for-in loop (version: 0)

Comparing performance of: Object.assign() vs Spread vs For-in (no hasOwnProperty check) vs For-in (direct hasOwnProperty check) vs For-in (indirect hasOwnProperty check)

Created: 3 years ago by: Guest

Jump to the latest result

Object.assign()

Spread

For-in (no hasOwnProperty check)

For-in (direct hasOwnProperty check)

For-in (indirect hasOwnProperty check)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A