Benchmark: test1235161321 - MeasureThat.net

Script Preparation code:

var arr = Array.from(Array(100).keys());

Tests:

`Array.slice(0)`
arr.slice(0);
`Array.length = N`
arr.length = 100;
`Object.assign([], arr)` with `Array.length = N`
var newArr = Object.assign([], arr); newArr.length = 100;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
`Array.slice(0)`
`Array.length = N`
`Object.assign([], arr)` with `Array.length = N`

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmarking test case on MeasureThat.net. The test evaluates the performance of different approaches for accessing and manipulating an array.

**Script Preparation Code**

The script preparation code `var arr = Array.from(Array(100).keys());` creates an array of 100 elements, where each element is a key from an array generated by `Array.from([])`. This setup prepares the array for testing.

**Html Preparation Code**

There is no HTML preparation code provided, which suggests that this benchmark only tests JavaScript code without considering DOM-related aspects.

**Test Cases**

The test case consists of three individual test cases:

1. **`Array.slice(0)`**: Tests the performance of `arr.slice(0)`, which creates a new array containing all elements from the original array.
2. **`Array.length = N`**: Tests the performance of accessing and manipulating an array's length using `arr.length = 100`.
3. **`Object.assign([], arr)` with `Array.length = N`**: Tests the performance of `Object.assign([], arr)`, which creates a new array by copying elements from the original array, followed by modifying the length of the resulting array.

**Options Compared**

These test cases compare the following options:

* Direct access to array elements using indexing (`arr.slice(0)` or `arr[0]`)
* Accessing and manipulating an array's length using assignment (`arr.length = 100`)
* Using `Object.assign()` to create a new array

**Pros and Cons of Each Approach**

1. **`Array.slice(0)`**:
	* Pros: Efficient for accessing a range of elements without modifying the original array.
	* Cons: Creates a new array, which can lead to memory allocation overhead.
2. **`Array.length = N`**:
	* Pros: Only modifies the length property of the existing array, potentially reducing memory allocation overhead.
	* Cons: May not be as efficient for large arrays due to the need to update the internal array data structure.
3. **`Object.assign([], arr)` with `Array.length = N`**:
	* Pros: Creates a new array and updates its length in a single operation, potentially reducing memory allocation overhead.
	* Cons: May not be as efficient as direct access for accessing individual elements.

**Library and Special JS Features**

The test case uses the following library:

* None explicitly mentioned, but `Array.from()` is a built-in method introduced in ECMAScript 2015 (ES6).

No special JavaScript features or syntax are used in this benchmark.

**Alternative Approaches**

Other alternatives for accessing and manipulating arrays might include:

* Using array methods like `map()`, `forEach()`, or `reduce()`
* Employing iterative approaches using loops
* Utilizing specialized libraries or frameworks optimized for performance

Note that these alternative approaches would likely have different pros and cons, and may not be relevant to the specific use case of this benchmark.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Windows

View result in a separate tab

Test name	Executions per second
`Array.slice(0)`	16813590.0 Ops/sec
`Array.length = N`	13203156.0 Ops/sec
`Object.assign([], arr)` with `Array.length = N`	24197.7 Ops/sec

Related benchmarks:

test1235161321 (version: 0)

Comparing performance of: `Array.slice(0)` vs `Array.length = N` vs `Object.assign([], arr)` with `Array.length = N`

Created: one year ago by: Guest

Jump to the latest result

`Array.slice(0)`

`Array.length = N`

`Object.assign([], arr)` with `Array.length = N`

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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