Benchmark: slice vs at vs pop v2

Script Preparation code:

arr = Array.from(Array(10000).keys())

Tests:

arr 0
arr[0]
arr length
arr[arr.length - 1]
at -1
arr.at(-1)
slice
arr.slice(-1)[0]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arr 0
arr length
at -1
slice

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The benchmark tests four different ways to access the first element, last element, and last element with a negative index in an array:

1. `arr[0]` (direct indexing)
2. `arr[arr.length - 1]` (indexing from the end of the array)
3. `arr.at(-1)` (using the `at()` method for negative indices)
4. `arr.slice(-1)[0]` (using the `slice()` method to get the last element)

**Options compared**

The four options are being compared in terms of their performance, which is measured by the number of executions per second.

**Pros and Cons of each approach:**

* **Direct indexing (`arr[0]`)**:
	+ Pros: Simple, efficient, and widely supported.
	+ Cons: May not be as readable or maintainable, especially for complex arrays.
* **Indexing from the end of the array (`arr[arr.length - 1]`)**:
	+ Pros: Can be more readable than direct indexing, especially for arrays with a large number of elements.
	+ Cons: May have performance implications due to the additional index calculation.
* **Using `at()` method for negative indices (`arr.at(-1)`)**:
	+ Pros: More readable and intuitive than direct indexing or indexing from the end of the array.
	+ Cons: Requires support for the `at()` method, which may not be available in all browsers or environments.
* **Using `slice()` method to get the last element (`arr.slice(-1)[0]`)**:
	+ Pros: Can be more readable than direct indexing, especially for arrays with a large number of elements.
	+ Cons: May have performance implications due to the additional method call and array creation.

**Library used**

In this benchmark, no specific library is being used. The `at()` method is a built-in JavaScript feature that was introduced in ECMAScript 2019.

**Special JS features or syntax**

None of the test cases use any special JavaScript features or syntax beyond what is covered by the standard language specification.

**Other alternatives**

If you wanted to test alternative ways to access array elements, some examples might include:

* Using `forEach()` method to iterate over the array and access the first element
* Using `map()` function to create a new array with the first element repeated
* Using `reduce()` method to accumulate the first element into an accumulator value

However, these alternatives would likely have different performance characteristics and may not be as efficient or readable as the original four options being tested.

Latest run results:

Run details: (Test run date: 11 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 120 on Android

View result in a separate tab

Test name	Executions per second
arr 0	3703348.0 Ops/sec
arr length	1852445.5 Ops/sec
at -1	3670903.5 Ops/sec
slice	2999081.0 Ops/sec

Related benchmarks:

slice vs at vs pop v2 (version: 0)

Comparing performance of: arr 0 vs arr length vs at -1 vs slice

Created: one year ago by: Guest

Jump to the latest result

arr 0

arr length

at -1

slice

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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