Benchmark: Testing pop vs index

Script Preparation code:

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

Tests:

Pop test
popLast(arr1, 9)
Index test
indexLast(arr1, 9)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Pop test
Index test

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested, compared, and discussed.

**What is being tested?**

The provided benchmark tests two approaches for accessing the last element of an array:

1. `popLast(arr, n)`: This function removes the last element from the array using `arr.pop()` and then checks if the removed element equals `n`.
2. `indexLast(arr, n)`: This function accesses the last element of the array by its index (`arr[arr.length - 1]`) and then checks if it equals `n`.

**What options are compared?**

The benchmark compares the performance of these two approaches:

* `popLast` (array method)
* `indexLast` (array access with indexing)

**Pros and Cons:**

* **Array Method (`popLast`)**:
	+ Pros:
		- Simpler implementation
		- Can be more efficient if the array is small, since it only requires a single `pop` operation.
	+ Cons:
		- May require more memory allocation or copying when removing elements from the end of the array, especially for large arrays.
* **Array Access with Indexing (`indexLast`)**:
	+ Pros:
		- Typically faster and more efficient than using `pop`, especially for large arrays.
	+ Cons:
		- Requires accessing the array by its length to get the index of the last element, which can be slower for small arrays.

**Library and Purpose**

In this benchmark, there is no specific library being used. The tests only involve standard JavaScript built-in methods (`pop`, `length`) and variables (arrays).

**Special JS Feature/Syntax**

There are no special JS features or syntax mentioned in the provided code.

**Other Considerations:**

* The benchmark assumes that the input array has at least one element.
* The test cases use a small array size of 10 elements, which may not accurately represent larger arrays. For larger arrays, the performance difference between `popLast` and `indexLast` might be negligible or dominated by other factors (e.g., caching, hardware).
* The benchmark does not account for edge cases like empty arrays, null/undefined inputs, or array modifications during the test.

**Alternatives**

Other approaches to accessing the last element of an array could include:

1. Using `slice()` method: `const arr = [0, 1, 2, ...]; const lastElement = arr.slice(-1)[0];`
2. Creating a separate function for getting the last element: `function getLast(arr) { return arr[arr.length - 1]; }`
3. Using a library like Lodash or Ramda, which provides utility functions for array manipulation.

Keep in mind that these alternatives might have different performance characteristics and trade-offs depending on the specific use case and requirements.

Related benchmarks:

Testing pop vs index (version: 0)

Comparing performance of: Pop test vs Index test

Created: 2 years ago by: Guest

Jump to the latest result

Pop test

Index test

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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