Benchmark: Array constructor vs literal performance (10 items)

Tests:

Array constructor - 10 items
var n = 10; var arr = new Array(n); for (var i = 0; i < n; i++) { arr[i] = i; }
Array literal - 10 items
var n = 10; var arr = []; for (var i = 0; i < n; i++) { arr.push(i); }
Array literal (assign by index) - 10 items
var n = 10; var arr = []; for (var i = 0; i < n; i++) { arr[i] = i; }
Array literal (explicit length) - 10 items
var n = 10; var arr = []; arr.length = n; for (var i = 0; i < n; i++) { arr[i] = i; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array constructor - 10 items
Array literal - 10 items
Array literal (assign by index) - 10 items
Array literal (explicit length) - 10 items

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Windows

View result in a separate tab

Test name	Executions per second
Array constructor - 10 items	8112736.0 Ops/sec
Array literal - 10 items	31976448.0 Ops/sec
Array literal (assign by index) - 10 items	26319300.0 Ops/sec
Array literal (explicit length) - 10 items	10709304.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its options.

**Benchmark Overview**

The test case measures the performance of different approaches to create an array in JavaScript:

1. Using the `Array` constructor with explicit length (`new Array(n)`).
2. Using the literal syntax with a fixed length (e.g., `[]` and then setting `length = n`).
3. Using the literal syntax without specifying a fixed length (e.g., `[]` and using `push` to add elements).

**Benchmark Definitions**

There are four test cases:

1. **Array constructor - 10 items**: Creates an array with explicit length using `new Array(n)`.
2. **Array literal - 10 items**: Creates an array with a fixed length using `[]` and then setting `length = n`.
3. **Array literal (assign by index) - 10 items**: Similar to the previous test case, but instead of setting `length`, it uses `push` to add elements.
4. **Array literal (explicit length) - 10 items**: Creates an array with a fixed length using `[]` and then setting `length = n`.

**Options Compared**

The benchmark compares the performance of three approaches:

1. **Explicit Length**: Using `new Array(n)` or `[]` followed by `length = n`.
2. **Push-based**: Using `[]` and adding elements using `push`, like in test case 3.
3. **Literal with Explicit Length**: Similar to explicit length, but uses a literal syntax (e.g., `[...]`) instead of `new Array(n)`.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **Explicit Length**:
	* Pros: Can be more efficient, especially when dealing with large arrays.
	* Cons: May lead to issues if the length is not set correctly.
2. **Push-based**:
	* Pros: More flexible, as it allows adding elements dynamically without having to specify a fixed length.
	* Cons: May be slower due to the repeated calls to `push`.
3. **Literal with Explicit Length**:
	* Pros: A balance between efficiency and flexibility.
	* Cons: May not be as efficient as explicit length for very large arrays.

**Library and Special JS Features**

There are no notable libraries or special JS features mentioned in the benchmark definitions.

**Other Alternatives**

If you're interested in exploring alternative approaches, consider the following:

1. **Using `Array.from()`**: A more modern approach to creating arrays from scratch.
2. **Using a library like Lodash's `createArray()` function**: Can provide additional flexibility and features.
3. **Using a different array creation syntax**, such as using `Map` or `Set`.

Keep in mind that the performance differences between these approaches may vary depending on the specific use case and JavaScript engine being used.

In summary, this benchmark provides a useful comparison of three common approaches to creating arrays in JavaScript, highlighting their pros and cons. The choice of approach ultimately depends on your specific requirements and preferences.

Related benchmarks:

Array constructor vs literal performance (10 items) (version: 0)

Comparing performance of: Array constructor - 10 items vs Array literal - 10 items vs Array literal (assign by index) - 10 items vs Array literal (explicit length) - 10 items

Created: 9 years ago by: Registered User

Jump to the latest result

Array constructor - 10 items

Array literal - 10 items

Array literal (assign by index) - 10 items

Array literal (explicit length) - 10 items

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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