Benchmark: Array pop-push vs last index element check

Script Preparation code:

var arr1 = [0,1,2,3,4,5,6,7,8,9];
var arr2 = [];

function pushPopLast(arr, n) {
  const element = arr.pop();
  arr.push(element);
  return element === n;
}

function indexLast(arr, n) {
  const element = arr[arr.lenght - 1];
  return element === n;
}

Tests:

pop-push check
pushPopLast(arr1, 8); pushPopLast(arr1, 9); pushPopLast(arr2, 9);
last-index check
indexLast(arr1, 8); indexLast(arr1, 9); indexLast(arr2, 9);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop-push check
last-index check

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
pop-push check	68508768.0 Ops/sec
last-index check	4686122.5 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 JSON and explain what is being tested, compared, and the pros/cons of different approaches.

**Benchmark Definition**

The benchmark definition defines two functions: `pushPopLast` and `indexLast`. Both functions are designed to check if an element is equal to a given value `n`.

*   `pushPopLast(arr, n)`: This function removes the last element from the array using `arr.pop()`, then pushes the removed element back into the array using `arr.push(element)`. Finally, it checks if the pushed element (which is now at the beginning of the array due to the push operation) is equal to the original value `n`.
*   `indexLast(arr, n)`: This function directly accesses the last index of the array using `arr[arr.length - 1]` and checks if its value equals the original value `n`.

**Options Compared**

The benchmark compares two approaches:

1.  Using the `pushPopLast` method
2.  Using the `indexLast` method

**Pros and Cons**

*   **Push-Pop Method (`pushPopLast`)**:
    *   Pros:
        *   This approach can be more efficient because it avoids accessing the end of the array.
        *   It might be more suitable for arrays that are frequently appended to or popped from.
    *   Cons:
        *   The `pop()` and `push()` operations have a higher overhead compared to direct indexing (`arr.length - 1`).
        *   If the array is very large, this approach could lead to slower performance due to the additional memory allocation and deallocation during push/pop operations.
*   **Last-Index Check (`indexLast`)**:
    *   Pros:
        *   This approach has a lower overhead since it directly accesses the last element of the array without any additional operations.
        *   It's likely to be faster for large arrays because it avoids the extra memory allocation and deallocation during push/pop operations.
    *   Cons:
        *   If the array is frequently appended to or popped from, this approach may not be as efficient since it needs to access the end of the array each time.

**Library**

The `pushPopLast` function uses JavaScript's built-in `Array.prototype.pop()` and `Array.prototype.push()` methods. These methods are part of the ECMAScript standard and are supported by most modern browsers and Node.js environments.

**Special JS Feature/Syntax**

There is no special JavaScript feature or syntax being used in this benchmark. It only relies on basic JavaScript features like arrays, loops, and function definitions.

**Alternative Approaches**

Other approaches to compare the performance of element checking might include:

*   Using `slice()` instead of `pop()` and `push()`: This would involve creating a new array with the desired element and comparing it to the original value.
*   Using `find()` or `indexOf()` methods: These methods search for an element in the array without removing it, but they might be slower if the array is large.
*   Using native WebAssembly support (if available): Some browsers now support executing WebAssembly code directly, which could potentially provide better performance.

Keep in mind that these alternative approaches may have their own set of pros and cons and might not necessarily outperform the `pushPopLast` or `indexLast` methods.

Related benchmarks:

Array pop-push vs last index element check (version: 1)

Comparing pop-push method vs last index check for an array element

Comparing performance of: pop-push check vs last-index check

Created: 7 years ago by: Registered User

Jump to the latest result

pop-push check

last-index check

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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