Benchmark: slice, splice - MeasureThat.net

Script Preparation code:

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

Tests:

slice
list = [...list.slice(0,500), 9999, ...list.slice(500)]
splice
list.splice(500, 0, 9999)

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:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:133.0) Gecko/20100101 Firefox/133.0

Browser/OS: Firefox 133 on Windows

View result in a separate tab

Test name	Executions per second
slice	102.0 Ops/sec
splice	1776.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**
The benchmark definition is a simple JavaScript code snippet that creates an array `list` with 1 million elements, and then performs two operations on it:

1. `slice`: A shallow copy of the first 500 elements of the array is created using `Array.prototype.slice()` method.
2. `splice`: The array is modified by inserting the number 9999 at index 500.

**Options Compared**
The benchmark compares the performance of two options:

* **Slice Method (`list = [...list.slice(0,500), 9999, ...list.slice(500)]`)**: This method creates a new array by taking a subset of the original array using `Array.prototype.slice()`. It then concatenates this subset with the remaining elements of the original array.
* **Splice Method (`list.splice(500, 0, 9999)`)**: This method modifies the original array in-place by inserting an element at a specific index.

**Pros and Cons**

**Slice Method**

Pros:

* Immutable: The `slice` method creates a new array without modifying the original one.
* Efficient for large datasets: Because it creates a new array, it can be more efficient than the `splice` method for large datasets.

Cons:

* Creates multiple arrays: Creating a new array using `slice()` involves creating a new object reference, which can lead to garbage collection overhead.
* Concatenation is expensive: The resulting array has two separate sections (before and after the insertion point), which can lead to additional memory allocation and copying.

**Splice Method**

Pros:

* In-place modification: The `splice` method modifies the original array without creating a new one, which can be more efficient.
* Fewer allocations: Because it modifies the original array, there are fewer allocations and copies involved.

Cons:

* Modifies the original array: This can lead to unexpected behavior if the benchmark is not careful to restore the original state.
* Inefficient for large datasets: For very large arrays, `splice` can be slower due to the overhead of inserting elements into the middle of the array.

**Library and Special Features**
There are no libraries used in this benchmark. However, it does use special JavaScript features:

* **Array.prototype.slice()**: This method is a part of the ECMAScript standard and allows creating a shallow copy of an array.
* **Array.prototype.splice()**: This method is also a part of the ECMAScript standard and allows modifying the original array in-place.

**Other Alternatives**
If you wanted to test alternative approaches, some possibilities include:

* Using `Array.from()` instead of `slice()` for creating a new array from an existing one.
* Using `concat()` or other methods for concatenating arrays instead of using the spread operator (`...`).
* Testing the performance of using `splice()` with different insertion points (e.g., at the beginning, end, or in the middle) compared to the current implementation.
* Comparing the performance of `slice()` and `splice()` on smaller datasets versus larger ones.

Keep in mind that these alternatives might change the nature of the benchmark, so it's essential to carefully consider how they affect the test cases and results.

Related benchmarks:

slice, splice (version: 0)

Comparing performance of: slice vs splice

Created: one year ago by: Guest

Jump to the latest result

slice

splice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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