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); }

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 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36

Browser/OS: Chrome 139 on Linux

View result in a separate tab

Test name	Executions per second
Array constructor - 1000 items	1227231.5 Ops/sec
Array literal - 1000 items	259380.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The provided benchmark measures the performance difference between two approaches to create an array in JavaScript:

1. **Array constructor**: Using the `new Array(n)` syntax, where `n` is the length of the array.
2. **Array literal**: Using the square bracket notation `[]`, followed by elements separated by commas.

**Options comparison**

The test case compares these two approaches with different lengths of arrays (1000 items). The goal is to determine which approach is faster for creating large arrays.

**Pros and Cons:**

* **Array constructor**:
	+ Pros:
		- Creates an empty array with the specified length, which can be useful for initializing array elements.
		- Might be more readable in certain contexts.
	+ Cons:
		- Requires extra memory to allocate the underlying buffer.
		- Can lead to slower performance due to the overhead of creating a new object.
* **Array literal**:
	+ Pros:
		- More concise and expressive syntax.
		- Faster performance since it doesn't require creating a new object or allocating memory.
	+ Cons:
		- Requires more memory for storing the array elements.
		- Might be less readable in certain contexts.

**Special JavaScript feature**

The test case uses a common JavaScript feature: **for loops with incrementing indices**. This is a fundamental concept in programming and is used extensively in arrays, objects, and other data structures.

**Library usage**

None of the provided benchmark cases use any external libraries. The tests are self-contained and rely on built-in JavaScript features.

**Other alternatives**

If you wanted to compare these approaches with additional methods for creating arrays, some possible alternatives could include:

* Using `Array.from()` or `Array.of()` (introduced in ES6) to create an array from an iterable.
* Utilizing libraries like Lodash or Underscore.js for array creation and manipulation.

However, since this benchmark focuses specifically on the `new Array(n)` vs. square bracket notation syntax, it's likely that these alternative methods would be excluded from the test case.

Keep in mind that the performance difference between these approaches can vary depending on the specific JavaScript engine, browser, or environment being used.

Related benchmarks:

Array constructor vs literal (version: 0)

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

Created: 9 years ago by: Guest

Jump to the latest result

Array constructor - 1000 items

Array literal - 1000 items

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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