Benchmark: Testing array concat vs spread

Tests:

One
const one = [{v:1}, {v:3}, {v:9}, {v:2}]; const two = [{v:3}, {v:12}, {v:4}, {v:2}]; console.log([...one, ...two])
Two
const one = [{v:1}, {v:3}, {v:9}, {v:2}]; const two = [{v:3}, {v:12}, {v:4}, {v:2}]; console.log(one.concat(two))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
One
Two

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 explain what's being tested.

The provided JSON represents a JavaScript microbenchmark that tests two approaches to concatenate arrays: using the spread operator (`...`) versus the `concat()` method.

**Approaches being compared:**

1. **Spread Operator (`...`)**: This approach uses the spread operator to concatenate two arrays. The syntax is: `const result = [...array1, ...array2]`. This method creates a new array with all elements from both input arrays.
2. **`concat()` Method**: This approach uses the `concat()` method to concatenate two arrays. The syntax is: `const result = array1.concat(array2)`. This method returns a new array with all elements from both input arrays, without modifying the original arrays.

**Pros and Cons of each approach:**

* **Spread Operator (`...`)**:
	+ Pros:
		- Creates a new array, which can be more efficient if you need to modify the result.
		- Can be used in many contexts, such as when working with destructuring or template literals.
	+ Cons:
		- Can lead to unnecessary object creation and garbage collection, especially for large arrays.
		- May not be as cache-friendly as the `concat()` method.
* **`concat()` Method**:
	+ Pros:
		- More cache-friendly, as it allows browsers to optimize the concatenation process.
		- Less overhead compared to creating a new array with the spread operator.
	+ Cons:
		- Returns a new array without modifying the original arrays.
		- May not be suitable for scenarios where you need to modify the result.

**Library and syntax considerations:**

None mentioned in this specific benchmark, but it's worth noting that some browsers may have optimized implementations of these methods or additional features like `Array.prototype.concat()` optimization.

**Other alternatives:**

* **For Arrays only:** Other approaches to concatenate arrays include using the `Push` method (e.g., `array1.push(...array2)`), but this can lead to unnecessary array resizing and reallocation.
* **In general:** For more complex data structures, other methods like the `Flatten()` or `Map()` functions might be used.

**Benchmark preparation code:**

The provided script preparation code is empty (`"Script Preparation Code": null`), which means that no specific setup is required for this benchmark. The test cases themselves define the input arrays and expected behavior.

Keep in mind that measuring performance differences between these approaches can depend on various factors, such as:

* Array size and complexity
* Browser version and platform
* JavaScript engine implementation

Related benchmarks:

Testing array concat vs spread (version: 0)

Comparing performance of: One vs Two

Created: 5 years ago by: Guest

Jump to the latest result

One

Two

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):