Benchmark: Some reorder test (not reverse)

Script Preparation code:

var list = [];
for (let i = 0; i < 10000; i++) {
  list.push(i);
}

Tests:

splice (non-mutating)
for(let i = 0; i < 5000; i++) { const result = Array.from(list); const [removed] = result.splice(9000, 1); result.splice(i, 0, removed); list = result; }
spread
for(let i = 0; i < 5000; i++) { list = [list[9000], ...list.slice(0, 9000), ...list.slice(9001)]; }
concat
for(let i = 0; i < 5000; i++) { list = [list[9000]].concat(list.slice(0,9000)).concat(list.slice(9001)); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splice (non-mutating)
spread
concat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.104 Safari/537.36

Browser/OS: Chrome 88 on Windows

View result in a separate tab

Test name	Executions per second
splice (non-mutating)	23.9 Ops/sec
spread	3.4 Ops/sec
concat	7.7 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript benchmark test case, and it's designed to measure the performance of reordering elements in an array.

**What is tested:**

The benchmark tests three different approaches to reorder the last element of an array:

1.  **Splice (non-mutating)**: This approach uses the `splice` method with two arguments to remove the last element and then insert it at a specified position.
2.  **Spread**: This approach uses the spread operator (`...`) to create a new array by copying the first part of the original array, removing the last element, creating a copy of the remaining elements, and then concatenating them with the removed element at the end.
3.  **Concat**: This approach uses the `concat` method to concatenate three arrays: one containing the removed element, one containing the remaining elements before the last one, and one containing the remaining elements after the last one.

**Options compared:**

These three approaches are compared in terms of their execution time on different devices.

**Pros and Cons:**

*   **Splice (non-mutating)**:

*   Pros:
        *   This approach is relatively efficient because it modifies the original array in place.
        *   It avoids creating intermediate arrays, which can reduce memory usage.
    *   Cons:
        *   The `splice` method has a higher overhead compared to other methods like spread and concat.
        *   The operation involves removing an element from the array, which can be costly.
*   **Spread**:

*   Pros:
        *   This approach creates new arrays in place of modifying the original one.
        *   It avoids using the `splice` method or the `concat` method with a large number of elements.
    *   Cons:
        *   Creating new arrays can be memory-intensive, especially for large arrays.
        *   The operation involves copying a significant portion of the array, which can slow down performance.
*   **Concat**:

*   Pros:
        *   This approach is simple and easy to understand.
        *   It avoids using intermediate arrays or the `splice` method.

*   Cons:
        *   Creating multiple temporary arrays can lead to high memory usage.
        *   The operation involves concatenating a large number of elements, which can slow down performance.

**Libraries:**

None of these test cases use any external libraries.

**Special JS features/syntax:**

There are no special JavaScript features or syntax used in these benchmark tests. They only utilize built-in methods and operators like `splice`, `concat`, and the spread operator (`...`).

**Alternatives:**

Other alternatives for reordering elements in an array include:

*   Using a custom loop to manually iterate over the array and insert or remove elements.
*   Utilizing data structures like queues or stacks, which are designed for inserting and removing elements at specific positions.
*   Leveraging modern JavaScript features like `Array.prototype.slice()` with a custom function to reorder elements.

However, these alternatives may not be as efficient as the approaches tested in this benchmark.

Related benchmarks:

Some reorder test (not reverse) (version: 0)

Testing reordering of elements in array.

Comparing performance of: splice (non-mutating) vs spread vs concat

Created: 3 years ago by: Guest

Jump to the latest result

splice (non-mutating)

spread

concat

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):