Benchmark: Slice vs Pop vs At(-1)

Script Preparation code:

var arr = [1, 3, 5, 11, 13, 123, 123 ,32, 123, 23213, 2323, 2313, 545];

Tests:

Slice
arr.slice(0, -1);
Pop
arr.pop();
At(-1)
arr.at(-1)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
Pop
At(-1)

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's break down the JavaScript microbenchmark on MeasureThat.net.

**Benchmark Definition**

The benchmark definition is a JSON object that defines the scope of the test. In this case, it only has a single property called "Script Preparation Code", which contains a JavaScript array `arr` with 11 elements. The script preparation code sets up the array and makes it available for use in the subsequent benchmark definitions.

**Individual Test Cases**

The individual test cases are designed to measure the performance of three different ways to access the last element of the array:

1. **Slice**: `arr.slice(0, -1)`. This method creates a new array that includes all elements up to but not including the last one.
2. **Pop**: `arr.pop()`. This method removes and returns the last element from the original array.
3. **At(-1)**: `arr.at(-1)`. This method is used in modern JavaScript versions (from ECMAScript 2020 onwards) to access an element at a specific index, where -1 refers to the last element.

**Options Compared**

The benchmark compares the performance of these three methods:

* Slice: creates a new array with all elements up to but not including the last one.
* Pop: removes and returns the last element from the original array.
* At(-1): accesses the last element directly using the `at` method.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Slice**: Pros:
	+ Creates a new array, which can be more efficient for small arrays or when working with large datasets.
	+ Can be faster than Pop for small arrays.
Cons:
	+ Creates an extra array object, which consumes memory.
	+ May not be as efficient for very large arrays.
* **Pop**: Pros:
	+ Removes and returns the last element directly from the original array.
	+ Can be more efficient for large arrays.
Cons:
	+ Removes the last element from the original array, making it invalid for subsequent operations.
	+ May cause unnecessary garbage collection.
* **At(-1)**: Pros:
	+ Accesses the last element directly without modifying the original array.
	+ Does not create an extra array object like Slice does.
Cons:
	+ Only available in modern JavaScript versions (from ECMAScript 2020 onwards).
	+ May have performance overhead due to the use of the `at` method.

**Other Considerations**

* When working with large arrays, Pop may be more efficient since it only removes and returns a single element from the original array.
* When working with small arrays or when creating new arrays, Slice may be faster since it creates an extra array object that can be more efficiently garbage collected.
* The `at` method in modern JavaScript versions provides a convenient way to access elements at specific indices without modifying the original array.

**Alternative Approaches**

Some alternative approaches could include:

* Using `indexOf` and `slice` methods together: `arr.slice(arr.indexOf(arr[arr.length - 1]))`. This approach avoids creating an extra array object but still has some overhead due to the use of `indexOf`.
* Using a pointer or index variable to access the last element directly: `var lastIndex = arr.length - 1; var lastElement = arr[lastIndex]`. This approach is simple and efficient but may not be suitable for all use cases.

However, these alternative approaches are not included in the benchmark on MeasureThat.net, so their performance characteristics are not compared.

Latest run results:

Run details: (Test run date: 25 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36 Edg/129.0.0.0

Browser/OS: Chrome 129 on Windows

View result in a separate tab

Test name	Executions per second
Slice	5676506.0 Ops/sec
Pop	9150129.0 Ops/sec
At(-1)	9059490.0 Ops/sec

Related benchmarks:

Slice vs Pop vs At(-1) (version: 0)

Comparing performance of: Slice vs Pop vs At(-1)

Created: 2 years ago by: Guest

Jump to the latest result

Slice

Pop

At(-1)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):