Benchmark: JavaScript spread operator vs Object.assign performance - tweld

Tests:

Using the spread operator
const firstObject = {} const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = {} 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: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36

Browser/OS: Chrome 81 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
Using the spread operator	17695386.0 Ops/sec
Using Object.assign	5518347.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark measures the performance difference between two methods for merging objects in JavaScript: the spread operator (`...`) and `Object.assign()`. The benchmark is designed to test which method is faster, more efficient, and scalable.

**Benchmark Definition JSON Analysis**

The benchmark definition JSON contains two main sections:

1. **Script Preparation Code**: This section is empty, which means that no custom code is required to set up the test environment.
2. **Html Preparation Code**: This section is also empty, indicating that no HTML-related setup is necessary for this benchmark.

**Individual Test Cases**

There are two test cases in total:

1. **Using the spread operator**
	* The benchmark definition code creates two objects: `firstObject` and `secondObject`. `firstObject` is an empty object, while `secondObject` has a property called `moreData` with the value `'foo bar'`.
	* The benchmark then uses the spread operator (`...`) to merge these two objects into a new object, `finalObject`.
2. **Using Object.assign**
	* Similar to the first test case, but instead of using the spread operator, it uses the `Object.assign()` method to merge `firstObject` and `secondObject` into `finalObject`.

**Library Use**

Neither of the benchmark definitions explicitly imports or uses any external libraries.

**Special JS Features/Syntax**

There is no special JavaScript feature or syntax used in this benchmark. It only relies on standard JavaScript syntax and built-in methods like the spread operator and `Object.assign()`.

**Performance Comparison**

The two test cases are designed to compare the performance of the spread operator versus `Object.assign()`. The results indicate that:

* Using the spread operator is significantly faster than using `Object.assign()` (average execution time per second: 17695386.0 vs 5518347.0, respectively).

**Pros and Cons of Different Approaches**

1. **Spread Operator (`...`)**:
	* Pros:
		+ Faster execution time.
		+ More concise syntax.
	* Cons:
		+ May not be supported in older browsers or versions of JavaScript.
2. **Object.assign()**:
	* Pros:
		+ Widely supported across different browsers and JavaScript versions.
		+ Easy to implement for developers familiar with object merging.
	* Cons:
		+ Slower execution time compared to the spread operator.

**Alternatives**

Other methods for merging objects in JavaScript include:

1. **Object.create()**: Creates a new object using an existing object as a prototype.
2. **Object.assign()` with multiple arguments: Passes multiple source objects to `Object.assign()` at once, which can be more efficient than calling it multiple times.
3. **Object.merge()` (non-standard): Some modern JavaScript engines and libraries support the `Object.merge()` method, which is similar to the spread operator.

Keep in mind that the performance difference between these methods may vary depending on the specific use case and browser/JavaScript environment.

Related benchmarks:

JavaScript spread operator vs Object.assign performance - tweld (version: 0)

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

Created: 4 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 one month ago):