Benchmark: structuredClone vs Object cloning for `Map<number, Set<number>>`

Script Preparation code:

const array_from = Array.from
const math_random = Math.random

function mapToObject (map) {
	const obj = {}
	map.forEach((value, key) => {
		obj[key] = array_from(value)
	})
	return obj
}

const randInt = (min, max) => ((math_random() * (max - min) + min) | 0)
var map_obj = new Map()
const add_random_entry = () => {
	map_obj.set(randInt(0, 2000), new Set(
		Array(randInt(0, 20)).fill(0).map(
			() => randInt(-500, 500)
		)
	))
}
for (let i = 0; i < 500; i++) { add_random_entry() }

Tests:

Object cloning
let obj = mapToObject(map_obj) // ensure that jit does not simply jump to disposing of obj obj[12] ? (obj[12][0] += 1) : delete obj[12] obj = undefined
structuredClone
let map_cloned = structuredClone(map_obj) // ensure that jit does not simply jump to disposing of map_cloned map_cloned.get(12) ? (map_cloned.get(12).add(-1)) : (map_cloned.set(12, new Set([5, 5, 5]))) map_cloned = undefined

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object cloning
structuredClone

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/118.0

Browser/OS: Firefox 118 on Ubuntu

View result in a separate tab

Test name	Executions per second
Object cloning	4803.0 Ops/sec
structuredClone	1380.2 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark compares two approaches for cloning a `Map<number, Set<number>>` object in JavaScript: manual object cloning using the `mapToObject()` function and the `structuredClone()` method.

**Test Case 1: Object Cloning (Manual)**

The first test case creates a `Map<number, Set<number>>` object `map_obj`, populates it with random entries, and then clones it manually using the `mapToObject()` function. The cloned object is used to perform operations on specific keys, ensuring that the JIT compiler does not optimize away the object.

**Pros:**

* Provides more control over the cloning process
* Can be optimized for specific use cases

**Cons:**

* More complex and error-prone due to manual management of objects
* May not work as expected in certain edge cases or with specific JavaScript versions

**Test Case 2: structuredClone()**

The second test case creates a `Map<number, Set<number>>` object `map_obj`, populates it with random entries, and then clones it using the `structuredClone()` method. The cloned map is used to perform operations on specific keys, ensuring that the JIT compiler does not optimize away the object.

**Pros:**

* Provides a high-level abstraction for cloning objects
* Less error-prone than manual object cloning

**Cons:**

* May be slower due to the overhead of the `structuredClone()` method
* Limited control over the cloning process

**Library: structuredClone()**

The `structuredClone()` method is a part of the Web APIs specification and is supported in modern browsers, including Firefox 118. It creates a deep copy of an object, including all its properties and children, without modifying the original object.

**Special JS Feature/Syntax: None**

This benchmark does not use any special JavaScript features or syntax.

**Other Alternatives**

If `structuredClone()` is not available or desired, other alternatives for cloning objects in JavaScript include:

* Using libraries like Lodash or Underscore.js
* Implementing a custom cloning function using recursive object traversal
* Using the `JSON.parse(JSON.stringify(obj))` method (note: this can be slower and may not work as expected with complex objects)

**Benchmark Preparation Code**

The provided script preparation code includes:

* Initialization of random number generators (`math_random`) and array creation functions (`array_from`)
* Creation of a `Map<number, Set<number>>` object `map_obj` with random entries
* A loop that adds random entries to the map for performance and reproducibility

**Html Preparation Code**

No HTML preparation code is provided.

Related benchmarks:

structuredClone vs Object cloning for `Map<number, Set<number>>` (version: 0)

Comparing performance of: Object cloning vs structuredClone

Created: one year ago by: Guest

Jump to the latest result

Object cloning

structuredClone

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):