Benchmark: JavaScript spread operator vs Object.assign performance (with empty object in Object.assign)

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36

Browser/OS: Chrome 92 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	1700981.2 Ops/sec
Using Object.assign	3743407.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: using the JavaScript spread operator (`...`) and using `Object.assign()` with an empty object as its second argument (`Object.assign({}, firstObject, secondObject)`).

**Options Compared**

1. **Using the Spread Operator (`...`)**:
	* Pros:
		+ More concise and readable code.
		+ Can be faster because it avoids the overhead of creating a new object using `Object.assign()`.
	* Cons:
		+ May require more modern JavaScript versions (ES6+) to work.
		+ Can be slower in older browsers that don't support the spread operator or have poor performance.
2. **Using `Object.assign()` with an Empty Object**:
	* Pros:
		+ Widely supported across older and newer browsers.
		+ Works regardless of JavaScript version.
	* Cons:
		+ More verbose code.
		+ May be slower due to the overhead of creating a new object using `Object.assign()`.

**Library Used**

In this benchmark, no specific library is used. However, it's worth noting that some libraries like Lodash or Ramda might provide alternative implementations for spreading objects or working with arrays, which could potentially affect performance.

**Special JS Feature/Syntax**

The spread operator (`...`) is a feature introduced in ECMAScript 2015 (ES6), and it allows you to expand an object into multiple arguments. This benchmark tests the performance of using this feature for object merging.

**Benchmark Preparation Code**

The script preparation code is empty, which means that the test only runs the provided JavaScript code without any additional setup or initialization.

**Other Alternatives**

If the spread operator is not available, alternative approaches to merge objects include:

* Using `Object.assign()` with multiple arguments: `Object.assign(firstObject, secondObject)`.
* Creating a new object and assigning properties using dot notation: `const finalObject = {}; finalObject.sampleData = firstObject.sampleData; finalObject.moreData = secondObject.moreData;`.
* Using the `concat` method or spread operator with arrays (not applicable for objects): `const finalArray = [...firstObject, ...secondObject];`.

These alternatives have different performance characteristics and trade-offs compared to using the spread operator or `Object.assign()`.

Keep in mind that this benchmark only compares two specific approaches and does not cover all possible scenarios or edge cases.

Related benchmarks:

JavaScript spread operator vs Object.assign performance (with empty object in Object.assign) (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign

Created: 3 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

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):