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

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: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	17606576.0 Ops/sec
Using Object.assign	12528956.0 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 world of JavaScript microbenchmarks on MeasureThat.net!

**What is being tested?**

The provided benchmark measures the performance difference between two approaches to merge objects: using the spread operator (`...`) and `Object.assign()`. The test case consists of three objects:

1. `firstObject`: containing a single property `sampleData` with value `'Hello world'`.
2. `secondObject`: containing a single property `moreData` with value `'foo bar'`.

The benchmark aims to determine which approach is faster when merging these two objects into a new object, `finalObject`.

**Options compared:**

There are two options being compared:

1. **Using the spread operator (`...`)**: This method uses the rest parameter syntax (`...objectName`) to create a new object and copies properties from `firstObject` and `secondObject` into it.
2. **Using `Object.assign()`**: This method creates a new object using the `Object.assign()` method, passing `firstObject`, `secondObject`, and an empty object as arguments.

**Pros and cons of each approach:**

* **Using the spread operator (`...`):**
	+ Pros:
		- More concise and readable code.
		- Less boilerplate code compared to using `Object.assign()`.
	+ Cons:
		- May be slower due to the syntax parsing overhead.
* **Using `Object.assign()`:**
	+ Pros:
		- Faster execution since it's a built-in method optimized for performance.
	+ Cons:
		- More verbose and less readable code.

**Library usage:**

None of the test cases explicitly use any JavaScript libraries. However, it's worth noting that `Object.assign()` is a built-in method in JavaScript, so no external library is necessary.

**Special JS feature or syntax:**

The spread operator (`...`) is a relatively recent addition to JavaScript (introduced in ECMAScript 2018). It allows for concise object merging and has become a popular choice among developers. However, as mentioned earlier, it might be slower due to the syntax parsing overhead.

**Other alternatives:**

If you're looking for alternative approaches to merge objects, consider:

1. **Using `Object.create()`**: This method creates a new object with the specified prototype, and then iterates over the properties of one or more source objects to copy them into the new object.
2. **Using `lodash.assign()` (or other utility libraries)**: If you're working in an environment where performance is critical, consider using optimized library functions like `lodash.assign()`, which may be faster than built-in methods.

In conclusion, the provided benchmark helps compare the performance of two popular approaches to merge objects in JavaScript: using the spread operator and `Object.assign()`. While the spread operator offers readability benefits, its syntax parsing overhead might result in slower execution times.

Related benchmarks:

JavaScript spread operator vs Object.assign performance - correct (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>

Fastest: N/A

Slowest: N/A

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