Benchmark: array spread operator vs concat vs push fix

Script Preparation code:

var a = Array.from({length: 2000}).map((_, i)=>`${i}`);
var b = Array.from({length: 2000}).map((_, i)=>`${i}`);

Tests:

spread
const c = [...a, ...b];
concat
const c = a.concat(b);
push
b.forEach((v) => a.push(v));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
concat
push

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/117.0.0.0 Safari/537.36

Browser/OS: Chrome 117 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
spread	78931.6 Ops/sec
concat	689797.4 Ops/sec
push	7376.2 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, the different approaches compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark is testing three approaches to merge two arrays: `array spread operator` (`a.push(...b)`), `concat` (`a.concat(b)`), and `push with forEach` (`b.forEach((v) => a.push(v))`). The benchmark is named "array spread operator vs concat vs push fix".

**Script Preparation Code**

The script preparation code sets up two arrays, `a` and `b`, each containing 2000 elements. These arrays are used as inputs for the different merge approaches.

**Html Preparation Code**

There is no HTML preparation code provided, which means that the benchmark only runs in a headless browser environment, likely using a tool like Selenium or Puppeteer.

**Individual Test Cases**

The three individual test cases are:

1. **spread**: `const c = [...a, ...b];`
2. **concat**: `const c = a.concat(b);`
3. **push**: `b.forEach((v) => a.push(v));`

Each test case has a different approach to merge the two arrays.

**Approaches Compared**

Here's a brief overview of each approach:

1. **Array Spread Operator (`a.push(...b)`)**:
	* Pros: Fast, efficient, and concise.
	* Cons: May not be supported in older browsers or environments.
	* Consideration: This approach is the most modern and efficient way to merge arrays. However, it may not work in older environments that don't support the spread operator.
2. **Concat** (`a.concat(b)`):
	* Pros: Widely supported across different browsers and environments.
	* Cons: May be slower and less efficient than the array spread operator.
	* Consideration: This approach is a more traditional way to merge arrays, but it can be slower and less efficient than the array spread operator.
3. **Push with forEach** (`b.forEach((v) => a.push(v))`):
	* Pros: Simple and easy to understand.
	* Cons: May be slower and less efficient than the other two approaches.
	* Consideration: This approach is not as efficient as the other two, but it can be useful in certain situations where readability is more important than performance.

**Library and Special JS Features**

There are no libraries or special JavaScript features used in this benchmark. The focus is solely on comparing the different merge approaches.

**Other Alternatives**

If you're interested in exploring alternative approaches to merging arrays, here are a few options:

1. `Array.prototype.reduce()`: This method can be used to merge two arrays by reducing them together.
2. `Array.prototype.slice()`: This method can be used to create a new array by slicing and concatenating the original arrays.
3. **Using `Map` objects**: You can use `Map` objects to merge two arrays, but this approach is not as straightforward as the others.

Keep in mind that these alternatives may have different performance characteristics or trade-offs, depending on your specific use case.

Related benchmarks:

array spread operator vs concat vs push fix (version: 1)

a.push(...b); // bug, not works!

Comparing performance of: spread vs concat vs push

Created: one year ago by: Registered User

Jump to the latest result

spread

concat

push

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):