Benchmark: PseudoArray to Array rest vs Array.from

HTML Preparation code:

<ul>
  <li>text</li>
  <li>text</li>
  <li>text</li>
 </ul>

Tests:

rest
let arr = document.querySelectorAll('li') let arrOutput = [...arr]
from
let arr = document.querySelectorAll('li') let arrOutput = Array.from(arr)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
rest
from

Fastest: N/A

Slowest: N/A

Latest run results:

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

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I'll break down the benchmark and explain what's being tested, compared options, pros and cons, and other considerations.

**Benchmark Overview**

The MeasurThat.net website allows users to create and run JavaScript microbenchmarks. The provided benchmark compares two approaches for converting a pseudo-array (created using `document.querySelectorAll`) to an actual array: the spread operator (`...`) and the `Array.from()` method.

**Test Cases**

There are two test cases:

1. "rest" - This test case uses the spread operator (`...`) to convert the pseudo-array to an actual array.
2. "from" - This test case uses the `Array.from()` method to convert the pseudo-array to an actual array.

**Library and Purpose**

In both test cases, the `document.querySelectorAll` function is used to create a pseudo-array. The `Array.prototype.slice()` or `Array.prototype.splice()` methods are not explicitly mentioned, but they are likely used internally by `querySelectorAll` to create a pseudo-array.

**Special JS Feature/Syntax**

There's no special JavaScript feature or syntax being tested in this benchmark. It's purely a comparison of two approaches for array creation.

**Options Compared**

The two options being compared are:

1. Spread Operator (`...`)
2. `Array.from()` method

**Pros and Cons of Each Approach:**

1. **Spread Operator (`...`)**:
	* Pros:
		+ Can be more concise and readable
		+ Works with most JavaScript versions
	* Cons:
		+ May lead to slower performance due to the overhead of creating a new array
		+ Does not provide any type safety or guarantees about the length of the resulting array
2. **`Array.from()` method**:
	* Pros:
		+ Provides more type safety and guarantees about the length of the resulting array
		+ Can be faster than the spread operator due to its optimized implementation
	* Cons:
		+ May require additional dependencies (e.g., `es5-shim` or a polyfill)
		+ Can be less concise and readable for some developers

**Other Considerations**

When choosing between these two approaches, consider the trade-offs between conciseness, readability, performance, and type safety. If you need more control over the resulting array's length or want to ensure better performance, `Array.from()` might be a better choice. However, if you prioritize brevity and ease of use, the spread operator could be a better fit.

**Other Alternatives**

There are other approaches for converting pseudo-arrays to actual arrays:

1. **`Array.prototype.slice()`**: This method creates a new array by copying elements from the original pseudo-array.
2. **`Array.prototype.splice()`**: This method can create an array by extracting elements from the pseudo-array, but it may modify the original array and is generally considered less safe than `Array.from()`.
3. **Using `Array` constructor directly**: You could use the `Array` constructor to explicitly create a new array from the pseudo-array.

However, these alternatives might not be as concise or readable as the spread operator or `Array.from()` methods, making them less preferred choices for most developers.

Related benchmarks:

PseudoArray to Array rest vs Array.from (version: 0)

Comparing performance of: rest vs from

Created: 2 years ago by: Guest

Jump to the latest result

rest

from

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):