Benchmark: Array Slicing - MeasureThat.net

Tests:

Array.slice
const elements = document.all; const arr = Array.prototype.slice.call(elements, 100, 200);
Array.push
const elements = document.all; const amount = elements.length; const arr = []; for (let i = 100; i < 200; i++) arr.push(elements[i]);
Array[index] with known size
const elements = document.all; const arr = Array(100); for (let i = 100; i < 200; i++) arr[i - 100] = elements[i];
Array[index] with unknown size
const elements = document.all; const arr = []; for (let i = 100; i < 200; i++) arr[i - 100] = elements[i];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.slice
Array.push
Array[index] with known size
Array[index] with unknown size

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/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.slice	3370281.2 Ops/sec
Array.push	217007.7 Ops/sec
Array[index] with known size	221830.6 Ops/sec
Array[index] with unknown size	218936.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Overview**

The benchmark tests different ways of getting a slice or subset of an array in JavaScript. The goal is to measure the performance of each approach, likely for optimization purposes.

**Options Compared**

The benchmark compares four approaches:

1. **Array.slice**: Uses the `slice()` method to create a new array with a specified start and end index.
2. **Array.push**: Creates an empty array and pushes elements into it using a loop, starting from the 100th element to the 200th element.
3. **Array[index] with known size**: Assigns values to a pre-allocated array of length 100, starting from the 100th index (index 0) to the 200th index.
4. **Array[index] with unknown size**: Similar to the previous approach, but assigns values to an empty array using a loop.

**Pros and Cons**

Here's a brief analysis of each approach:

1. **Array.slice**:
	* Pros: Creates a new array, which can be useful for immutability or avoiding side effects.
	* Cons: May incur additional overhead due to the creation of a new array.
2. **Array.push**:
	* Pros: Can be efficient if the array is already large and only needs to append elements.
	* Cons: Creates an empty array, which may lead to performance issues if the array grows significantly.
3. **Array[index] with known size**:
	* Pros: Avoids the overhead of creating a new array or pushing elements into an existing one.
	* Cons: Requires pre-allocating memory for the array, which can be resource-intensive.
4. **Array[index] with unknown size**:
	* Similar to the previous approach, but assigns values to an empty array using a loop.

**Libraries and Special Features**

None of the test cases use any libraries or special features in JavaScript. The focus is on comparing different array methods.

**Considerations**

When writing similar benchmarks, consider the following:

1. **Use meaningful names**: Use descriptive names for variables, functions, and arrays to make the benchmark easier to understand.
2. **Test edge cases**: Include test cases that cover edge scenarios, such as large or small arrays, to ensure comprehensive results.
3. **Optimize loop performance**: When using loops, optimize their performance by minimizing overhead, using efficient algorithms, and avoiding unnecessary computations.

**Alternatives**

If you need to benchmark different array methods, consider alternatives like:

1. **Array.from()**: Creates a new array from an iterable or an array-like object.
2. **Array.prototype.map()**: Applies a transformation function to each element of the array and returns a new array with the results.
3. **Array.prototype.filter()**: Returns a new array containing only elements that pass the test implemented by the provided function.

Keep in mind that the choice of alternative methods depends on your specific use case and performance requirements.

Related benchmarks:

Array Slicing (version: 0)

Different ways of getting a slice of an array

Comparing performance of: Array.slice vs Array.push vs Array[index] with known size vs Array[index] with unknown size

Created: one year ago by: Guest

Jump to the latest result

Array.slice

Array.push

Array[index] with known size

Array[index] with unknown size

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):