Benchmark: Object.assign vs spread operator

Tests:

Object.assign
var params = { b:"hello", c: true, d:7 }; var other = Object.assign({ a: 2 }, params);
spread operator
var params = { b:"hello", c: true, d:7 }; var other = { a: 2, ...params };
jQuery extend
var params = { b:"hello", c: true, d:7 }; var other = $.extend({ a: 2 }, params);
Manual Update
var params = { b:"hello", c: true, d:7 }; params.a = 2; params.b = "NEW TEXT";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
spread operator
jQuery extend
Manual Update

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Windows

View result in a separate tab

Test name	Executions per second
Object.assign	4463205.5 Ops/sec
spread operator	10108732.0 Ops/sec
jQuery extend	0.0 Ops/sec
Manual Update	86916600.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares the performance of four approaches to merge or update objects:

1. `Object.assign`
2. Spread operator (`{...params}`)
3. jQuery's `.extend()` method
4. Manual updates by directly modifying the object properties

**What is being tested?**

Each test case measures the execution time of a specific approach when performing one of the following operations:

* Merging two objects (e.g., `Object.assign` or spread operator)
* Updating an existing object's properties (e.g., "Manual Update")

**Comparison Options and Pros/Cons:**

1. **Object.assign**: This method creates a new object with the target object as its prototype, then copies all enumerable own properties from the source object to the target object.
	* Pros:
		+ Wide support across browsers
		+ Simple and readable syntax
	* Cons:
		+ Creates a new object, which can be memory-intensive for large datasets
2. **Spread operator (`{...params}`)**: This method creates a new object by spreading the properties of `params` onto an existing object.
	* Pros:
		+ Efficient and concise syntax
		+ No memory overhead, as it updates the existing object in-place
	* Cons:
		+ Requires modern JavaScript version support (ES6+)
3. **jQuery extend**: This method creates a new object with merged properties from two sources.
	* Pros:
		+ Familiar syntax for jQuery developers
		+ Wide support across browsers that have jQuery
	* Cons:
		+ jQuery is not required, which can add overhead due to loading and parsing the library
4. **Manual Update**: This approach updates an existing object's properties directly.
	* Pros:
		+ No memory overhead, as no new objects are created
	* Cons:
		+ Can be error-prone if not done carefully (e.g., losing original property values)

**Library and Special JavaScript Features**

The benchmark uses jQuery's `.extend()` method, which relies on the `$.extend` function. This function is a part of the jQuery library.

No special JavaScript features are used in this benchmark beyond ES6 syntax support for the spread operator.

**Benchmark Preparation Code and Results**

The benchmark preparation code is empty for all test cases, indicating that the focus is solely on comparing the performance of each approach.

The provided benchmark results show that:

* The "Manual Update" approach has the highest execution time
* The spread operator (`{...params}`) has a significantly lower execution time than `Object.assign`
* jQuery's `.extend()` method returns 0 executions per second, indicating a potential issue or optimization problem

Keep in mind that benchmark results can be influenced by various factors, such as:

* JavaScript engine and browser performance
* Object sizes and complexity
* Memory constraints and allocation patterns

These results should not be taken as absolute truth but rather as an approximation of performance characteristics under specific conditions.

Related benchmarks:

Object.assign vs spread operator (version: 0)

Comparing performance of: Object.assign vs spread operator vs jQuery extend vs Manual Update

Created: 7 years ago by: Guest

Jump to the latest result

Object.assign

spread operator

jQuery extend

Manual Update

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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