Benchmark: Deep Clone Object: JSON.parse vs Object.assign

Script Preparation code:

var obj = {a: "hello", c: "test", po: 33, arr: [1, 2, 3, 4], anotherObj: {a: 33, str: "whazzup"}};

Tests:

JSON.parse
var obj2 = JSON.parse(JSON.stringify(obj));
Object.assign
var obj2 = Object.assign({}, obj);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
JSON.parse
Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 11 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
JSON.parse	2309681.2 Ops/sec
Object.assign	17436006.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested.

**Benchmark Purpose**

The benchmark is designed to compare two approaches for creating a deep clone of an object in JavaScript:

1. Using `JSON.parse(JSON.stringify(obj))`
2. Using `Object.assign({}, obj)`

**Approaches Comparison**

Both approaches aim to create a new, independent copy of the original object `obj`. However, they differ in their implementation:

* **JSON.parse(JSON.stringify(obj))**: This method uses the `JSON.stringify()` function to serialize the object and then parses the resulting string back into an object using `JSON.parse()`. The `JSON.stringify()` function can create a deep clone of objects that implement the `JSONSerializable` interface, which includes many built-in JavaScript types like arrays, dates, numbers, etc.
* **Object.assign({}, obj)**: This method uses the spread operator (`...`) to create a shallow copy of an object and then uses `Object.assign()` to assign the cloned properties to a new object. While this approach is simple and widely supported, it may not work correctly for nested objects that contain other objects as values.

**Pros and Cons**

Here are some pros and cons of each approach:

* **JSON.parse(JSON.stringify(obj))**:
	+ Pros: Can create deep clones of complex objects, works well with many built-in JavaScript types.
	+ Cons: May not work correctly for objects that don't implement `JSONSerializable`, can be slower due to string serialization.
* **Object.assign({}, obj)**:
	+ Pros: Simple and widely supported, works well for shallow copies.
	+ Cons: May not create deep clones of complex objects, may produce unexpected results if the original object has circular references.

**Library Used**

In this benchmark, no specific library is used. However, `JSON.stringify()` relies on the JSON serializer in your JavaScript implementation, which might be a built-in part of the browser or a separate module.

**Special JS Features or Syntax**

None are explicitly mentioned in the provided benchmark definition.

**Other Alternatives**

Other approaches for creating deep clones of objects include:

* Using `Object.assign()` with an object that has the same structure as the original object, but uses different variables to create the clone.
* Implementing a custom cloning function using recursion or iteration.
* Using libraries like Lodash or Immutable.js that provide built-in cloning functions.

Keep in mind that these alternatives might have their own pros and cons, which are not detailed here.

Related benchmarks:

Deep Clone Object: JSON.parse vs Object.assign (version: 1)

Comparing performance of: JSON.parse vs Object.assign

Created: 6 years ago by: Registered User

Jump to the latest result

JSON.parse

Object.assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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