Benchmark: Slice vs. Splice

Script Preparation code:

var list = [];
var rowIndex = 300
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}

Tests:

slice
list = [...list.slice(0, rowIndex), 1000, ...list.slice(rowIndex)]
splice
list.splice(rowIndex, 0, 1000)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
splice

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what is tested on MeasureThat.net.

**Benchmark Definition**

The benchmark definition provides a script preparation code and an HTML preparation code (which is empty in this case). The script preparation code creates an array `list` with 1 million elements, starting from index 0. This setup allows us to measure the performance of different methods for inserting or removing elements at specific indices.

**Test Cases**

There are two test cases:

1. **Slice**: The first test case uses the `slice()` method to create a new array that includes the first `rowIndex` (300) elements, followed by a single element (`1000`), and finally the remaining elements.
2. **Splice**: The second test case uses the `splice()` method to insert a single element at index `rowIndex` (300).

**Options Compared**

In this benchmark, we're comparing two methods:

*   **Slice**: Creates a new array by slicing the original array from the beginning up to the specified index (`rowIndex`) and then pushes a new element onto the resulting array.
*   **Splice**: Modifies the original array by inserting an element at the specified index (`rowIndex`).

**Pros and Cons of Each Approach**

Here are some pros and cons for each approach:

*   **Slice**:
    *   Pros:
        *   Faster, as it only involves creating a new array and pushing elements onto it.
        *   Less memory-intensive since it doesn't modify the original array.
    *   Cons:
        *   Creates a new array which can be expensive in terms of performance for large datasets.

*   **Splice**:
    *   Pros:
        *   Modifies the original array, reducing memory allocation and garbage collection overhead.
        *   Can be more efficient when dealing with very large arrays or datasets.
    *   Cons:
        *   Slower due to the modification of the original array.
        *   More memory-intensive since it involves modifying the original array.

**Library: None**

There are no libraries used in this benchmark. The `slice()` and `splice()` methods are built-in JavaScript functions that work on arrays.

**Special JS Feature/Syntax: None**

There are no special JavaScript features or syntaxes used in this benchmark.

**Alternative Approaches**

Other approaches to consider when inserting or removing elements from an array include:

*   **Array.prototype.push() + Array.prototype.shift()**: Pushing an element onto the end of the array and then shifting all subsequent elements one position forward.
*   **Array.prototype.unshift()**: Adding a single element at the beginning of the array.

Related benchmarks:

Slice vs. Splice (version: 0)

Comparing performance of: slice vs splice

Created: 4 years ago by: Guest

Jump to the latest result

slice

splice

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):