Benchmark: Array constructor vs literal

Tests:

Array constructor - 1000 items
var n = 100000; var arr = new Array(n); for (var i = 0; i < n; i++) { arr[i] = i; }
Array literal - 1000 items
var n = 100000; var arr = []; for (var i = 0; i < n; i++) { arr.push(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array constructor - 1000 items
Array literal - 1000 items

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_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Browser/OS: Chrome 53 on Mac OS X 10.12.0

View result in a separate tab

Test name	Executions per second
Array constructor - 1000 items	968.3 Ops/sec
Array literal - 1000 items	907.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and other considerations.

**Benchmark Definition**

The benchmark is called "Array constructor vs literal". It measures the performance difference between creating an array using the `new Array` syntax versus creating an array directly with square brackets (`[]`).

**Script Preparation Code**

The script preparation code for this benchmark is empty. This means that the JavaScript engine has to create a new scope and variables every time the test runs.

**Html Preparation Code**

There is no html preparation code provided for this benchmark.

**Individual Test Cases**

There are two individual test cases:

1. "Array constructor - 1000 items"
This test case creates an array using the `new Array` syntax and fills it with 1000 elements in a loop.
2. "Array literal - 1000 items"
This test case creates an array directly with square brackets (`[]`) and fills it with 1000 elements in a loop.

**Comparison**

The two test cases are compared to determine which method is faster for creating large arrays.

**Options Compared**

The options being compared are:

* `new Array` syntax
* Directly creating an array with square brackets (`[]`)

**Pros and Cons of Each Approach**

1. **`new Array` Syntax**
	* Pros: Can be used to create arrays with specific length, can be useful for array-based data structures.
	* Cons: May incur additional overhead due to the creation of a new object and prototype chain.
2. **Directly Creating an Array with Square Brackets (`[]`)**
	* Pros: Lightweight, fast, and flexible.
	* Cons: Does not provide explicit length information, may lead to unexpected behavior if not used carefully.

**Library Used**

There is no library explicitly mentioned in the benchmark definition or test cases.

**Special JS Feature or Syntax**

None of the provided test cases use any special JavaScript features or syntax.

**Other Considerations**

* The benchmark uses a loop to fill the array with elements, which can add overhead due to the repeated iterations.
* The `for` loop used in both test cases may not be the most efficient choice for large arrays. Consider using more modern iterative methods like `Array.prototype.fill()` or `for...of`.
* The benchmark is run on a Chrome browser version 53, which may have some performance characteristics different from newer versions.

**Alternatives**

If you want to explore alternative approaches, consider the following:

* Use a library like `array-prototype-extensible` to create extensible arrays.
* Experiment with other array creation methods, such as using `Set` or `Map`.
* Use more modern JavaScript features like `Array.from()` or `Array.prototype.map()` to create arrays.

Keep in mind that these alternatives may introduce new variables, dependencies, or performance characteristics, so be sure to thoroughly test and optimize your implementation.

Related benchmarks:

Array constructor vs literal (version: 0)

Comparing performance of: Array constructor - 1000 items vs Array literal - 1000 items

Created: 8 years ago by: Guest

Jump to the latest result

Array constructor - 1000 items

Array literal - 1000 items

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):