Benchmark: Array creation types

Script Preparation code:

var length = 10000

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; }
Push
var array = []; for (var index = 0; index < length; index++){ array.push(index); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Empty init
Sized init
Push

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.98 Safari/537.36

Browser/OS: Chrome 54 on Mac OS X 10.11.6

View result in a separate tab

Test name	Executions per second
Empty init	1215.9 Ops/sec
Sized init	1240.8 Ops/sec
Push	1195.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into explaining the JavaScript microbenchmark you've provided.

**Benchmark Overview**

The benchmark measures the performance of different ways to create an array in JavaScript. The benchmark consists of three test cases:

1.  **Empty init**: Creating an empty array using `var array = []`.
2.  **Sized init**: Creating a sized array using `var array = new Array(length)`.
3.  **Push**: Using the `push()` method to add elements to an existing array.

**Options Compared**

The benchmark compares the performance of these three approaches:

*   **Empty Init ( var array = [] )**: This approach creates an empty array and then populates it with elements using a loop.
*   **Sized Init ( var array = new Array(length) )**: This approach creates a sized array directly, which can be more efficient than the `push()` method for large arrays.
*   **Push ( var array.push(index); )**: This approach uses the `push()` method to add elements to an existing array.

**Pros and Cons of Each Approach**

Here's a brief overview of the pros and cons of each approach:

### Empty Init ( var array = [] )

Pros:

*   Easy to understand and implement.
*   Works well for small arrays or arrays with few elements.

Cons:

*   Creating a new array can be expensive, especially for large arrays.
*   The loop may introduce overhead due to the JavaScript engine's optimization mechanisms.

### Sized Init ( var array = new Array(length) )

Pros:

*   Can be more efficient than creating an empty array and then populating it with elements.
*   Directly creates a sized array without any intermediate steps.

Cons:

*   Not all JavaScript engines support this syntax, or the performance difference might not be significant.
*   The code may look less intuitive to some developers due to the need for the `length` variable.

### Push ( var array.push(index); )

Pros:

*   Highly flexible and can be used with existing arrays.
*   Reduces memory allocation because it doesn't create a new array.

Cons:

*   Can be slower than creating an array directly or using `new Array(length)`.
*   May have performance issues when dealing with very large numbers of elements.

**Library Usage**

There is no library usage in this benchmark. However, the use of JavaScript engines and versions could impact the results due to differences in features support, optimizations, and performance characteristics.

**Special JS Features/Syntax**

This benchmark does not explicitly test or utilize any special JavaScript features/syntax beyond standard ECMAScript syntax and engine-specific optimizations.

Related benchmarks:

Array creation types (version: 0)

Comparing performance of: Empty init vs Sized init vs Push

Created: 8 years ago by: Guest

Jump to the latest result

Empty init

Sized init

Push

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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