Benchmark: Clone Array - 07/02/2024

Script Preparation code:

var arr1 = [1, 2, 3, , 5, 6, 7, 7, 8, 9, 10];

var arrCopy = null;

Tests:

Spread operator clone
arrCopy = [...arr1];
Structured clone
arrCopy = structuredClone(arr1);

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Spread operator clone

6.1M/s

Structured clone

345K/s

Fastest: Spread operator clone (17.6x faster)

View exact numbers

✓ Spread operator clone: 6,063,976 ops/sec
• Structured clone: 344,559 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread operator clone
Structured clone

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

Browser/OS: Chrome 124 on Windows

View result in a separate tab

Spread operator clone

6.1M/s

Structured clone

345K/s

View exact numbers

Test name	Executions per second
✓ Spread operator clone	6,054,960 Ops/sec
Structured clone	344,559 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and provide insights on what's being tested.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that tests two approaches for cloning an array: the spread operator (`[...arr1]`) and the `structuredClone` function.

**Script Preparation Code**

The script preparation code defines an array `arr1` with 10 elements, including some null values. This array is used as the input for the benchmarking test cases.

**Html Preparation Code**

There is no HTML preparation code provided, which means that only JavaScript performance testing will be performed on this benchmark.

**Benchmark Test Cases**

The benchmark consists of two individual test cases:

1. **Spread Operator Clone**: This test case measures the performance of cloning an array using the spread operator (`[...arr1]`). The idea behind this approach is to create a new array by iterating over each element in `arr1` and copying it to the new array.
2. **Structured Clone**: This test case measures the performance of cloning an array using the `structuredClone` function, which was introduced in ECMAScript 2020 as a way to create a deep copy of an object or array without recursively traversing the data structure.

**Libraries and Special JS Features**

In this benchmark, no special JavaScript features or syntax are being tested. However, it's worth noting that the `structuredClone` function is a relatively new addition to the JavaScript language, so its performance characteristics may still be evolving.

**Pros and Cons of Different Approaches**

Here are some pros and cons of each approach:

* **Spread Operator Clone**:
	+ Pros: Simple and intuitive, works well for small arrays.
	+ Cons: Can be slow for large arrays due to the need to create a new array and iterate over each element.
* **Structured Clone**:
	+ Pros: Fast and efficient for cloning arrays, as it uses optimized internal algorithms.
	+ Cons: May not work correctly with certain types of data or objects.

**Other Alternatives**

If you're looking for alternative approaches to cloning an array in JavaScript, some options include:

* Using `Array.prototype.slice()` or `Array.prototype.concat()`: These methods can be used to create a shallow copy of an array, but may not work correctly if the array contains nested objects or arrays.
* Using a library like Lodash's `cloneDeep()` function: This function provides a robust and efficient way to clone complex data structures.

**Conclusion**

In summary, this benchmark tests two approaches for cloning an array in JavaScript: the spread operator (`[...arr1]`) and the `structuredClone` function. The spread operator approach is simple but may be slow for large arrays, while the structured clone approach is fast and efficient but may not work correctly with certain types of data or objects.

Clone Array - 07/02/2024 (version: 0)

Comparing performance of: `Spread operator clone vs Structured clone`

Created: 2 years ago by: Guest

Go to the latest result

Spread operator clone

Structured clone

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Clone Array - 07/02/2024 (version: 0)

Comparing performance of: Spread operator clone vs Structured clone

Created: 2 years ago by: Guest

Go to the latest result

Spread operator clone

Structured clone

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Spread operator clone vs Structured clone`