Benchmark: Using SPREAD operator to change a reference

Script Preparation code:

myObject = {a: 1, b: 2, c: 3}

Tests:

A new clone via Object.assing
clonedObjectA = Object.assign(myObject);
A new clone via spread operator
clonedObjectB = {...myObject};

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
A new clone via Object.assing
A new clone via spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

Browser/OS: Firefox 65 on Windows

View result in a separate tab

Test name	Executions per second
A new clone via Object.assing	23075276.0 Ops/sec
A new clone via spread operator	4724317.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON benchmark definition and explain what is being tested, compared options, pros/cons of each approach, library usage, special JavaScript features or syntax (if applicable), and other considerations.

**Benchmark Definition:**
The benchmark defines two test cases to measure the performance difference between using `Object.assign()` and the spread operator (`{...}`) to create a new copy of an object. The script preparation code creates a simple object `myObject` with three properties (`a`, `b`, and `c`) and assigns it to a variable.

**Individual Test Cases:**
There are two test cases:

1. **"A new clone via Object.assign()"**: This test case uses the `Object.assign()` method to create a shallow copy of `myObject`. The benchmark definition is `clonedObjectA = Object.assign(myObject);`.
2. **"A new clone via spread operator"**: This test case uses the spread operator (`{...}`) to create a new object that inherits properties from `myObject`. The benchmark definition is `clonedObjectB = {...myObject};`.

**Options Compared:**
The two options being compared are:

1. **`Object.assign()` method**: Creates a shallow copy of an object, copying all enumerable own properties to a new object.
2. **Spread operator (`{...}`)**: Creates a new object that inherits properties from the original object.

**Pros and Cons of Each Approach:**

* `Object.assign()`:
	+ Pros:
		- Widely supported across browsers
		- Can be used to assign multiple values to an object
	+ Cons:
		- Performs a shallow copy, which may not work as expected if the original object has nested objects or arrays
		- Can lead to unexpected behavior if the original object is modified externally
* Spread operator (`{...}`):
	+ Pros:
		- Creates a new, independent copy of the object
		- Supports nested objects and arrays
	+ Cons:
		- Only supported in modern browsers (from ECMAScript 2015 onwards)
		- May require more memory to create a deep copy

**Library Usage:**
None of the test cases use any external libraries.

**Special JavaScript Features or Syntax (if applicable):**
Neither test case uses any special features or syntax, as both options are standard methods in modern JavaScript. The spread operator was introduced in ECMAScript 2015 and is widely supported across browsers.

**Other Considerations:**

* The benchmark measures the performance of creating a new clone of an object using two different methods.
* The test cases use small objects (`myObject`) to minimize the overhead of object creation and property assignment.
* The benchmark result will show which method performs better in terms of execution speed, taking into account factors like browser version, device platform, operating system, and number of executions per second.

**Alternatives:**
Other methods for creating a new copy of an object include:

1. `Object.create()` with `Object.assign()`: Creates a new object using `Object.create()` and then assigns properties to it using `Object.assign()`.
2. `JSON.parse(JSON.stringify())`: A widely supported method, but not as efficient as the spread operator.
3. Using a library like Lodash's `cloneDeep()` function (for deeper cloning of objects).

These alternatives may have their own trade-offs in terms of performance, memory usage, and browser support.

Related benchmarks:

Using SPREAD operator to change a reference (version: 0)

Comparing performance of: A new clone via Object.assing vs A new clone via spread operator

Created: 6 years ago by: Guest

Jump to the latest result

A new clone via Object.assing

A new clone via spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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