Benchmark: Object cloning comparision

Script Preparation code:

var obj = {
	type: 'price',
	amount: '123',
	vatPercentage: 22,
	vatIncluded: true,
	vatId: 124153,
  	nestedObj: {
  		item1: 'abc',
  		item2: undefined
	}
};

var copy = undefined;

Tests:

Spread
copy = {...obj};
structuredClone
copy = structuredClone(obj);
JSON
copy = JSON.parse(JSON.stringify(obj));
simple assignment
copy = obj;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
structuredClone
JSON
simple assignment

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Browser/OS: Chrome 110 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Spread	9849380.0 Ops/sec
structuredClone	549982.1 Ops/sec
JSON	983565.8 Ops/sec
simple assignment	12121797.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and its implications.

**Benchmark Overview**

The provided benchmark compares four different methods for cloning (i.e., creating a copy of) an object in JavaScript:

1. **Spread Operator (`...`)**: Creating a shallow copy of an object by spreading its properties using the syntax `copy = {...obj};`.
2. **structuredClone()**: A new function introduced in ECMAScript 2020, which can be used to create a deep clone of an object.
3. **JSON.parse(JSON.stringify(obj))**: Using the JSON.stringify() method to serialize the object and then parsing the resulting string as JSON to recreate the original object.
4. **Simple Assignment (`obj`)**: Simply assigning the value of `obj` to a new variable, effectively creating a shallow copy.

**Options Comparison**

Here's a brief overview of each option:

1.  **Spread Operator (`...`):**
    *   Pros:
        *   Simple and concise syntax.
        *   Shallow copies are sufficient for many cases.
    *   Cons:
        *   Only creates a shallow copy, which may not work as expected if the original object has nested objects with complex structures.
        *   May not handle certain data types or properties correctly (e.g., functions, undefined values).
2.  **structuredClone()**
    *   Pros:
        *   Creates a deep clone of an object, preserving all its properties and nested structures.
        *   Handles various data types and properties, including functions and undefined values.
    *   Cons:
        *   Introduced in ECMAScript 2020, so it may not be supported by older browsers or environments.
        *   May be slower due to the complexity of creating a deep clone.
3.  **JSON.parse(JSON.stringify(obj))**
    *   Pros:
        *   Widely supported across different JavaScript implementations and versions.
        *   Can handle complex data structures, including functions and undefined values.
    *   Cons:
        *   May not work as expected if the original object contains cyclic references or other complexities.
        *   May be slower due to the overhead of serializing and parsing the JSON string.

**Library Usage**

The benchmark uses the following libraries:

1.  **structuredClone()**: Built-in in ECMAScript 2020, no external library needed.
2.  **JSON.parse(JSON.stringify(obj))**: Built-in, no external library needed.

**Special JS Feature/Syntax**

This benchmark does not use any special JavaScript features or syntax beyond the methods being tested.

**Other Alternatives**

If you need to clone objects in a different context or with specific requirements, consider the following alternatives:

*   **Lodash's _.cloneDeep()**: A popular utility library that provides a deep-clone function for various data types.
*   **JSON.stringify() with a custom replacer function**: You can use JSON.stringify() with a custom replacer function to control how certain properties are handled during cloning.

Related benchmarks:

Object cloning comparision (version: 0)

Comparing performance of: Spread vs structuredClone vs JSON vs simple assignment

Created: one year ago by: Guest

Jump to the latest result

Spread

structuredClone

JSON

simple assignment

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):