Benchmark: Array constructor vs literal

Tests:

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

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what is being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark definition specifies that it compares three approaches:

1. `Array constructor` (using the `new Array()` syntax)
2. `Array literal` (using the square bracket `[]` syntax without the `var` keyword)
3. `Array literal index` (similar to the previous one, but with the syntax `arr[i] = i;` instead of `arr.push(i)`)

**What is being tested?**

In this benchmark, we're measuring the performance difference between three ways to create an array in JavaScript: using the constructor syntax, the literal syntax without the `var` keyword, and the literal syntax with indexing (`arr[i] = i;`).

**Pros and Cons of each approach**

1. **Array Constructor**
	* Pros:
		+ More explicit way of creating an array
	* Cons:
		+ May incur a performance overhead due to the creation of an object and its properties
2. **Array Literal (without `var` keyword)**
	* Pros:
		+ Less memory allocation, as it's just an array reference
	* Cons:
		+ May not be as explicit or readable as the constructor syntax
3. **Array Literal Indexing (`arr[i] = i;`)**
	* Pros:
		+ Similar to using `[]`, but with the added benefit of indexing
	* Cons:
		+ Can lead to performance issues if used in a loop, as it's an additional operation

**Library and Special JS Features**

There are no libraries mentioned in this benchmark. However, note that some JavaScript engines may use optimization techniques or caching mechanisms that could affect the results.

**Test Considerations**

The test runs each benchmark 1000 times (as specified by `n=1000`) to get a representative measure of performance. The results are likely influenced by factors such as:

* Browser and engine version
* Device platform and operating system
* System resources and memory available

**Other Alternatives**

If you're looking for similar benchmarks or alternatives, you can try:

* ECMAScript 2015 (ES6) vs. ES5: A comparison of the new features introduced in ES6, such as arrow functions, classes, and template literals.
* Loop vs. Array.prototype.forEach(): A benchmark comparing the performance of traditional loops with `Array.prototype.forEach()`.
* Function vs. Closure: A test evaluating the performance difference between defining a function versus using an immediately invoked function expression (IIFE).

Keep in mind that these benchmarks can help you understand the performance characteristics of different JavaScript approaches, but they might not reflect your specific use case or environment.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:108.0) Gecko/20100101 Firefox/108.0

Browser/OS: Firefox 108 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Array constructor - 1000 items	280621.0 Ops/sec
Array literal - 1000 items	193739.6 Ops/sec
Array literal index - 1000 items	200633.9 Ops/sec

Related benchmarks:

Array constructor vs literal (version: 0)

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

Created: 8 years ago by: Guest

Jump to the latest result

Array constructor - 1000 items

Array literal - 1000 items

Array literal index - 1000 items

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):