Benchmark: JavaScript spread operator vs Object.assign performance (single clone)

Tests:

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

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

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

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Let's break down the benchmark and its components.

**What is being tested?**

The benchmark measures the performance difference between two JavaScript methods: the spread operator (also known as the rest parameter syntax) and `Object.assign`. The test case involves creating an object with two properties (`sampleData` and `moreData`) using both methods, resulting in a single final object.

**Options compared:**

Two options are being compared:

1. **Using the spread operator**: This method uses the `...` symbol to create a new object that includes all properties from `firstObject`, which is then merged with any additional properties provided.
2. **Using `Object.assign()`**: This method creates a shallow copy of an object using the `Object.assign()` function, passing in the target object (`finalObject`) and multiple source objects (in this case, only one: `firstObject`).

**Pros and cons:**

1. **Using the spread operator:**
	* Pros:
		+ More concise and readable syntax.
		+ Can be used with multiple source objects to merge properties in a more intuitive way.
	* Cons:
		+ May be slower due to the overhead of creating a new object and iterating over its properties.
2. **Using `Object.assign()`**:
	* Pros:
		+ Generally considered faster than using the spread operator, as it avoids the overhead of creating a new object.
	* Cons:
		+ Requires multiple function calls (`Object.assign()` + object literals), which can be less readable and more cumbersome.

**Other considerations:**

When choosing between these two methods, consider the following factors:

* **Readability**: If code readability is important, using the spread operator might be a better choice.
* **Performance**: If performance is critical, using `Object.assign()` might be preferable due to its potential speed advantage.
* **Complexity**: As the number of source objects increases, using multiple `Object.assign()` calls can become cumbersome. In contrast, the spread operator allows for more intuitive merging of properties.

**Library usage:**

There are no external libraries used in this benchmark, making it a simple, self-contained test case.

**Special JS features or syntax:**

The spread operator (rest parameter syntax) is a modern JavaScript feature introduced in ECMAScript 2015. It's supported by most modern browsers and Node.js environments.

Related benchmarks:

JavaScript spread operator vs Object.assign performance (single clone) (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>

Fastest: N/A

Slowest: N/A

No previous run results

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