Benchmark: Array with and without predefined size

Tests:

Array predefined size
const arr = Array(10000); for (let i = 0; i < 10000; i++) { arr[i] = i * 2; }
Array no size
const arr = []; for (let i = 0; i < 10000; i++) { arr[i] = i * 2; }
array no size (push)
const arr = []; for (let i = 0; i < 10000; i++) { arr.push(i * 2); }
Array predefined size (large)
const arr = Array(1000000); for (let i = 0; i < 1000000; i++) { arr[i] = i * 2; }
Array no size (large)
const arr = []; for (let i = 0; i < 1000000; i++) { arr[i] = i * 2; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array predefined size
Array no size
array no size (push)
Array predefined size (large)
Array no size (large)

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark JSON and explore what's being tested, compared options, pros and cons, library usage, special JavaScript features, and alternative approaches.

**Benchmark Overview**

The "Array with and without predefined size" benchmark consists of four individual test cases:

1. **Array predefined size**: Creates an array of 10,000 elements using `Array(10000)` and fills them with values.
2. **Array no size**: Creates an empty array and then pushes 10,000 elements into it using a `for` loop.
3. **array no size (push)**: Similar to the previous test, but uses `push()` method instead of manual indexing.
4. **Array predefined size (large)**: Creates an array of 1,000,000 elements and fills them with values.

**Comparison**

The benchmark tests two approaches for creating and filling arrays:

* Manual indexing (`arr[i] = i * 2;`)
* Pushing elements onto the end of the array using `push()` method

Both methods have their own strengths and weaknesses:

* **Manual indexing**: Pros:
	+ Can be more efficient for small to medium-sized arrays.
	+ Allows for more control over memory allocation.
	+ Often preferred in older JavaScript versions (pre-ES6).
* **Pushing elements onto the end of the array**: Pros:
	+ More flexible and dynamic, as it doesn't require manual indexing.
	+ Can be faster for larger arrays due to the optimized `push()` method.
	+ Widely used and supported in modern JavaScript versions (post-ES6).

**Cons**

* Manual indexing can lead to slower performance on modern browsers due to the overhead of array resizing.
* Pushing elements onto the end of the array can lead to slower performance for smaller arrays, as it requires more memory allocations.

**Library Usage**

The benchmark uses `Array(10000)` and `push()` method, which are built-in JavaScript features. No external libraries or frameworks are required.

**Special JavaScript Features**

None mentioned in this explanation.

**Alternative Approaches**

Other ways to create and fill arrays include:

* Using `Array.prototype.fill()` method (ES6+): Fills an array with a single value.
* Using `Array.from()` method (ES6+): Creates a new array from an iterable source, such as an array or string.
* Using `Array.prototype.map()` method (ES6+): Applies a transformation function to each element in the original array.

These alternatives might be worth exploring for different use cases, but are not directly relevant to this specific benchmark.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:105.0) Gecko/20100101 Firefox/105.0

Browser/OS: Firefox 105 on Windows

View result in a separate tab

Test name	Executions per second
Array predefined size	7366.0 Ops/sec
Array no size	4013.7 Ops/sec
array no size (push)	3966.1 Ops/sec
Array predefined size (large)	70.8 Ops/sec
Array no size (large)	69.3 Ops/sec

Related benchmarks:

Array with and without predefined size (version: 0)

Comparing performance of: Array predefined size vs Array no size vs array no size (push) vs Array predefined size (large) vs Array no size (large)

Created: 2 years ago by: Guest

Jump to the latest result

Array predefined size

Array no size

array no size (push)

Array predefined size (large)

Array no size (large)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):