Benchmark: Slice vs pop array with N elements

Tests:

Array.pop() once the array exceeds 25 items
let arr = [] for (let i = 0; i < 10000; i++) { arr.push(i) if (arr.length > 25) { arr.pop() } }
Array.slice(0,25)
let arr = [] for (let i = 0; i < 10000; i++) { arr.push(i) arr.slice(0,25) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.pop() once the array exceeds 25 items
Array.slice(0,25)

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) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36

Browser/OS: Chrome 113 on Windows

View result in a separate tab

Test name	Executions per second
Array.pop() once the array exceeds 25 items	33305.8 Ops/sec
Array.slice(0,25)	2356.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark measures the performance of two different approaches for accessing and manipulating an array: `Array.pop()` after exceeding a certain length threshold, and `Array.slice(0, 25)`.

**Test Case 1: Array.pop() once the array exceeds 25 items**

This test case creates an array of 10,000 elements using a loop and pushes each element onto the array. Once the array has more than 25 elements, it checks if the array's length is greater than 25, and if so, pops the last item from the array.

**Test Case 2: Array.slice(0, 25)**

This test case creates an array of 10,000 elements using a loop and pushes each element onto the array. Then, it calls `Array.slice(0, 25)` to extract a subset of the first 25 elements from the array.

**Library Used**

In both test cases, no specific library is used beyond the built-in JavaScript Array methods.

**Special JS Features/Syntax**

None are explicitly mentioned in the provided benchmark definitions. However, it's worth noting that some modern browsers and JavaScript engines may optimize certain operations or use alternative internal implementations, which could affect performance. Nevertheless, this benchmark focuses on the basic syntax and behavior of these methods.

**Pros and Cons of Different Approaches:**

1. **Array.pop()**: This method has a time complexity of O(1) since it directly removes the last element from the array. However:
	* It modifies the original array, which may not be desirable if you need to preserve the data.
	* If the array is large, popping elements can lead to reallocations and copying of data, impacting performance.
2. **Array.slice()**: This method has a time complexity of O(n) since it creates a new array with the specified subset of elements. However:
	* It does not modify the original array, preserving its integrity.
	* Creating a new array can be expensive in terms of memory allocation and copying.

**Other Alternatives**

For this specific use case, other approaches might include:

1. **Using `Array.prototype.splice()`**: This method has a time complexity of O(n) since it replaces elements at the specified index range with new elements or removes them if no replacement value is provided.
2. **Using `Array.from()`**: If you need to create a new array from an existing one, this method can be more efficient than slicing and assigning.

Keep in mind that these alternatives may not necessarily outperform the original methods for every use case, as the performance difference often depends on the specific scenario and JavaScript engine implementation.

**Benchmark Result Interpretation**

The provided benchmark results show two different performance profiles:

* `Array.pop() once the array exceeds 25 items`: This test case executes approximately 33.3 executions per second.
* `Array.slice(0, 25)`: This test case executes approximately 2.36 executions per second.

This suggests that for this specific use case, using `Array.pop()` is significantly faster than using `Array.slice()`. However, the actual performance difference might vary depending on the specific use case and JavaScript engine implementation.

Related benchmarks:

Slice vs pop array with N elements (version: 0)

Benchmarking slicing(0, N) and checking if array.length > N and popping the last item

Comparing performance of: Array.pop() once the array exceeds 25 items vs Array.slice(0,25)

Created: one year ago by: Guest

Jump to the latest result

Array.pop() once the array exceeds 25 items

Array.slice(0,25)

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):