Benchmark: Destructuring array iterator vs array iterator keys

Script Preparation code:

var array_length = 30;

Tests:

Array from array iterator keys
const result = [...Array(array_length).keys()].map(x => ({ number: x + 1 }));
Array from array iterator alone
const result = [...Array(array_length)].map(x => ({ number: x + 1 }));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array from array iterator keys
Array from array iterator alone

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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**What is being tested?**

The provided benchmark tests two approaches to creating an array of objects from an array of numbers:

1. **Array.from() with array iterator keys**: This approach uses the `Array.from()` method and iterates over the keys of a new array created using `Array(array_length).keys()`. The resulting array is then mapped over to create an array of objects.
2. **Array from array iterator alone**: In this case, the benchmark creates a new array using `Array(array_length)` and maps over it directly.

**Comparison of options**

Both approaches have their pros and cons:

*   **Array.from() with array iterator keys**:
    *   Pros: This approach can be more concise and expressive when dealing with arrays that don't have numerical indices.
    *   Cons: It might incur additional overhead due to the iteration over an iterator object, which could potentially lead to slower performance in some cases.
*   **Array from array iterator alone**:
    *   Pros: This approach avoids the potential overhead of iterating over an iterator object and can be more straightforward when dealing with arrays that have numerical indices.
    *   Cons: It might become less concise or readable when working with non-numerical index arrays.

**Library usage**

Neither benchmark uses any libraries, as they are built-in JavaScript features. However, if you were to use a library like Lodash (e.g., `_.map()`) to achieve the same results, it would be an alternative approach.

**Special JS feature or syntax**

The benchmarks utilize a modern JavaScript feature called "template literals" (`x => ({ number: x + 1 })`). This syntax is used to create objects with dynamic values. The template literal syntax allows you to embed expressions inside string literals, creating a concise way to define the object's properties.

**Other alternatives**

Some other alternative approaches to achieving this result without using `Array.from()` would be:

*   Using `forEach()`: Create an array of numbers and then use `forEach()` along with the callback function (`(x) => ({ number: x + 1 })`) to create an object.
*   Using `reduce()`: Similar to `map()`, you could use `reduce()` to create the array of objects.

Here's a quick example of how you might achieve this using `forEach()`:

```javascript
var array_length = 30;
const result = Array(array_length).fill(0).map((x, i) => ({ number: x + i }));
```

And here's an example with `reduce()`, although it would be less efficient than the original approach since you're creating a new array:

```javascript
var array_length = 30;
const result = Array(array_length).fill(0).reduce((acc, _, i) => ({ number: acc.number + (i + 1) }), {});
```

Keep in mind that these alternative approaches will likely be less efficient than the original `Array.from()` method and might not provide a clear performance advantage.

Related benchmarks:

Destructuring array iterator vs array iterator keys (version: 0)

Comparing performance of: Array from array iterator keys vs Array from array iterator alone

Created: 2 years ago by: Registered User

Jump to the latest result

Array from array iterator keys

Array from array iterator alone

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):