Benchmark: push vs length as filter (2)

Script Preparation code:

var length = 2000;

const array = Array(length);
for (let i = 0, { length } = array; i < length; i += 1) {
  array[i] = i;
}

function push() {
  var a = [];
  for (let i = 0; i < length; i += 1) {
    if (i % 2) {
     a.push(i);
    }
  }
  return a;
}

function append() {
  var a = Array(length);
  var offset = 0;
  for (let i = 0; i < length; i += 1) {
    if (i % 2) {
      a[offset++] = i;
    }
  }
  a.length = offset;
  return a;
}

function filter() {
	return array.filter((v) => v % 2);
}

Tests:

push
var a = push();
length
var a = append();
filter
var a = filter();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push
length
filter

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 explanation of the provided JSON benchmark.

**Benchmark Overview**

The benchmark is designed to compare three different approaches for filtering an array: using `push()`, using `append()` with manual length adjustment, and using the built-in `filter()` method.

**Approaches Compared**

1. **Push():**
	* This approach creates a new array `a` and pushes elements from the original array `array` into it using the `push()` method.
	* The loop iterates over the entire array, but only pushes every other element (i.e., `i % 2 === true`).
	* This approach is likely to be slower due to the overhead of creating a new array and pushing elements into it.
2. **Append():**
	* This approach creates an array `a` with a fixed length equal to the original array's length.
	* The loop iterates over the entire array, but only assigns every other element (`i % 2 === true`) to the corresponding index in the new array.
	* After filling the array, the length of the array is adjusted to match the actual number of elements added (`a.length = offset;`).
	* This approach might be faster than `push()` since it doesn't involve creating a new array, but it requires manual memory management and adjustment of the array's length.
3. **Filter():**
	* This approach uses the built-in `filter()` method to create a new array containing only every other element from the original array (`array.filter((v) => v % 2)`).
	* The `filter()` method is likely to be faster since it's a native JavaScript function optimized for performance.

**Pros and Cons**

* **Push():**
	+ Pros: Easy to understand, minimal memory allocation.
	+ Cons: Creates a new array, pushes elements in individual operations, may lead to unnecessary allocations.
* **Append():**
	+ Pros: Only uses existing memory, potentially faster than `push()`.
	+ Cons: Requires manual length adjustment, can be slower due to allocation and deallocation overhead.
* **Filter():**
	+ Pros: Native JavaScript function, optimized for performance, minimal memory allocation.
	+ Cons: May require additional parsing and filtering operations.

**Library Usage**

The benchmark uses the `Array` object and its methods (`push()`, `append()`) without any external libraries. However, it's worth noting that some browsers may have additional features or optimizations enabled in their JavaScript engines.

**Special JS Features/Syntax**

There are no special JS features or syntax mentioned in this benchmark. All code is written using standard JavaScript syntax and doesn't utilize any experimental features like ES modules, async/await, or decorators.

**Alternative Approaches**

Other approaches to filtering an array might include:

* Using `map()` instead of `filter()`, which returns a new array with the filtered elements.
* Using a library like Lodash or Ramda for more complex filtering operations.
* Using native WebAssembly (WASM) functions to accelerate performance-critical code paths.

Keep in mind that these alternatives may not be relevant to this specific benchmark, and their performance impact would depend on the specific use case.

Related benchmarks:

push vs length as filter (2) (version: 0)

Comparing performance of: push vs length vs filter

Created: 2 years ago by: Registered User

Jump to the latest result

push

length

filter

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):