Benchmark: JavaScript spread operator vs Slice/Splice performance - 2

Script Preparation code:

const ITERATIONS = 500000;
var index = ITERATIONS/2;
var n = Math.random();

var list = [];
for (let i = 0; i < length; i += 1) {
  list.push(Math.random());
}

Tests:

Array clone with spread operator
const clone = [...list];
Array clone with slice
const clone = list.slice();
Array addition with spread operator
const clone = [...list, n];
Array addition with slice and push
const clone = list.slice(); clone.push(n);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array clone with spread operator
Array clone with slice
Array addition with spread operator
Array addition with slice and push

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 12 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array clone with spread operator	24496918.0 Ops/sec
Array clone with slice	123318128.0 Ops/sec
Array addition with spread operator	21418496.0 Ops/sec
Array addition with slice and push	27682086.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript benchmarks.

**Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided benchmark involves testing the performance of different methods for creating array clones, adding elements to an array using spread operators, and modifying existing arrays with `slice()` or push().

**Benchmark Definition**

The benchmark definition provides two main sections:

1. **Script Preparation Code**: This section is used to set up the test environment. It defines a constant `ITERATIONS` and calculates an index `n` based on this value. Then, it creates an empty array `list` and populates it with random numbers using a `for` loop.
2. **Html Preparation Code**: This section is currently blank, which means that the benchmark does not require any HTML setup.

**Individual Test Cases**

The test cases are defined in the `Benchmark Definition` section:

1. **Array Clone with Spread Operator**: The benchmark tests creating an array clone using the spread operator (`const clone = [...list];`).
2. **Array Clone with Slice**: The benchmark tests creating an array clone using the `slice()` method (`const clone = list.slice();`).
3. **Array Addition with Spread Operator**: The benchmark tests adding an element to the end of the array using the spread operator (`const clone = [...list, n];`).
4. **Array Addition with Slice and Push**: The benchmark tests adding an element to the end of the array using `slice()` followed by `push() (`const clone = list.slice();\r\nclone.push(n);`).

**Library: None**

Since none of the test cases use a library, there are no additional dependencies or configurations required.

**Special JS Features/Syntax**

None of the test cases require any special JavaScript features or syntax. They only utilize built-in language constructs like arrays, loops, and assignment operators.

**Options Compared**

The benchmark compares four different approaches:

1. Array clone with spread operator
2. Array clone with slice
3. Array addition with spread operator
4. Array addition with slice and push

These options are compared in terms of performance, which is likely the focus of the benchmark.

**Pros and Cons of Different Approaches**

Here's a brief summary of each approach:

1. **Array Clone with Spread Operator**: Pros: Simple, concise syntax; Cons: May have performance overhead due to creating a new array.
2. **Array Clone with Slice**: Pros: Fast, efficient way to create an array clone; Cons: Requires extra memory allocation for the new array.
3. **Array Addition with Spread Operator**: Pros: Easy to read and maintain; Cons: May be slower than `slice()` + `push()`.
4. **Array Addition with Slice and Push**: Pros: Fast, efficient way to add an element to the end of an array; Cons: Requires extra memory allocation for the new array.

**Other Considerations**

The benchmark results may also depend on factors like:

* JavaScript engine performance
* Browser version and platform
* Array size and complexity
* RAM availability

Keep in mind that these considerations might not be explicitly stated in the benchmark definition but can influence the overall outcome.

**Alternative Approaches**

If you're interested in exploring alternative approaches, here are a few:

1. Using `Array.prototype.concat()`: This method creates a new array by concatenating the existing array with the provided elements.
2. Utilizing `Array.from()`**: This method creates a new array from an iterable (like an array or string) and can be used to create clones or add elements.
3. Leveraging native WebAssembly support**: Some browsers support WebAssembly, which allows for optimized performance-critical code.

However, these alternatives might not be directly relevant to the specific benchmark being tested in this example.

Related benchmarks:

JavaScript spread operator vs Slice/Splice performance - 2 (version: 0)

Comparing performance of: Array clone with spread operator vs Array clone with slice vs Array addition with spread operator vs Array addition with slice and push

Created: 5 years ago by: Guest

Jump to the latest result

Array clone with spread operator

Array clone with slice

Array addition with spread operator

Array addition with slice and push

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):