Benchmark: Array creation types

Script Preparation code:

var length = 1000

Tests:

Empty init
var array = []; for (var index = 0; index < length; index++){ array[index] = index; }
Sized init
var array = new Array(length); for (var index = 0; index < length; index++){ array[index] = index; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Empty init
Sized init

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Windows

View result in a separate tab

Test name	Executions per second
Empty init	221324.8 Ops/sec
Sized init	380889.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what is tested in this benchmark.

The provided JSON represents two test cases: "Empty init" and "Sized init". These test cases are designed to measure the performance difference between creating an empty JavaScript array using two different approaches:

1. **Empty init**: In this approach, an empty array is created by simply initializing it as `var array = [];`. This method does not preallocate memory for the array.
2. **Sized init**: In this approach, a new array is created with a specified size using `var array = new Array(length);`. This method preallocates memory for the array.

**Options being compared:**

* Two approaches to create an empty JavaScript array
* Performance difference between these two approaches

**Pros and Cons of each approach:**

1. **Empty init ([])**:
	* Pros:
		+ Memory-efficient, as it only allocates space for the array's metadata.
		+ Can lead to better performance when working with small arrays or in memory-constrained environments.
	* Cons:
		+ May require more JavaScript engine overhead to manage and extend the array.
2. **Sized init (new Array(length))**:
	* Pros:
		+ Provides a clear and explicit size for the array, making it easier to reason about its behavior.
		+ Can lead to better performance when working with large arrays or in scenarios where memory is not a concern.
	* Cons:
		+ Allocates more memory upfront, which can be detrimental in memory-constrained environments.

**Library/Functionality:**

In this benchmark, no specific library or function is used. The test cases only rely on the built-in JavaScript array functionality.

**Special JS feature/Syntax:**

There are no special JavaScript features or syntaxes used in these test cases. They focus solely on comparing two approaches to create an empty array.

Now, let's consider alternative approaches:

* **Array constructor**: Another way to create an array is using the `Array()` constructor, like this: `var array = new Array(length)`. This approach is similar to the "Sized init" method but uses a different syntax.
* **Typed arrays**: For performance-critical code or in scenarios where memory is not a concern, typed arrays (e.g., `Uint8Array`, `Int32Array`) can provide better performance than regular arrays.

In summary, this benchmark measures the performance difference between creating an empty JavaScript array using two approaches: initializing it as an empty array (`[]`) and preallocating memory with `new Array(length)`.

Related benchmarks:

Array creation types (version: 0)

Comparing performance of: Empty init vs Sized init

Created: 9 years ago by: Guest

Jump to the latest result

Empty init

Sized init

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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