Benchmark: Array.from() vs new Array() - empty

Tests:

new Array()
new Array(500).fill({})
Array.from()
Array.from({ length: 500 })

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Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array()
Array.from()

Fastest: N/A

Slowest: N/A

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

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Let's dive into explaining the benchmark.

**What is tested:**

The provided benchmark compares two approaches to create filled arrays in JavaScript:

1. `new Array()`: This method creates an empty array and then fills it with a specified value using the `fill()` method.
2. `Array.from()`: This method creates a new array from an iterable (in this case, an object) and fills it with a specified value.

**Options compared:**

The benchmark compares the performance of these two approaches:

* `new Array()` with `new Array(500).fill({})` as the test case for creating filled arrays.
* `Array.from()` with `Array.from({ length: 500 })` as the test case for creating filled arrays.

**Pros and Cons:**

1. **`new Array()`:**
	* Pros:
		+ Simple and straightforward way to create an array.
		+ Can be used to create arrays of any size, not just fixed sizes.
	* Cons:
		+ May have performance overhead due to the need to fill the entire array with a value.
		+ Requires additional code to fill the array, which can add complexity.
2. **`Array.from()`:**
	* Pros:
		+ More concise and expressive way to create arrays from iterables.
		+ Can be used to create arrays of any size, not just fixed sizes.
		+ Typically has better performance than `new Array()` due to the optimized implementation.
	* Cons:
		+ Requires knowledge of the `Array.from()` method, which may not be familiar to all developers.

**Library and purpose:**

`Array.from()` is a built-in JavaScript method introduced in ECMAScript 2015 (ES6). Its purpose is to create a new array from an iterable source, such as an object or an array. In this benchmark, `Array.from()` is used to create a new array with a specified length and filled value.

**Special JS feature:**

The benchmark uses the `fill()` method, which is not a special JavaScript feature per se, but rather a part of the language that allows arrays to be filled with a specific value. However, some developers might be familiar with it as an optimization technique for creating large arrays.

**Other considerations:**

* The benchmark only tests the performance difference between `new Array()` and `Array.from()` when creating filled arrays. It does not account for other use cases where these methods are used.
* The test cases use fixed sizes (500) to simplify the comparison, but in real-world scenarios, sizes may vary.

**Alternatives:**

Other alternatives to create filled arrays include:

* Using a loop to create and fill an array:
```javascript
const arr = [];
for (let i = 0; i < 500; i++) {
  arr.push({});
}
```
* Using the `Array.from()` method with an empty object as the iterable source, like this:
```javascript
const arr = Array.from({ length: 500 }, () => {});
```
These alternatives may have different performance characteristics and trade-offs compared to `new Array()` and `Array.from()`.

Related benchmarks:

Array.from() vs new Array() - empty (version: 0)

Testing the difference between creating filled arrays.

Comparing performance of: new Array() vs Array.from()

Created: 3 years ago by: Guest

Jump to the latest result

new Array()

Array.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):