Benchmark: new array vs array length

HTML Preparation code:

<script>
    var test = [1, 2, 3]
</script>

Tests:

new array
test = []
length
test.length = 0

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new array
length

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark definition and test cases to explain what's being tested, compared, and analyzed.

**What is being tested?**

The main goal of this benchmark is to compare the performance difference between two approaches:

1. Creating an empty array using `new Array()`.
2. Accessing the length property of an existing array (`test.length = 0`).

These tests aim to measure how long it takes for a JavaScript engine (in this case, Chrome 88) to execute each approach.

**Options compared**

Two options are being compared:

1. **Creating an empty array**: `new Array()`
2. **Accessing the length property of an existing array**: `test.length = 0`

**Pros and Cons:**

*   Creating an empty array using `new Array()`:
    *   Pros: It creates a new, empty object that can be used as needed.
    *   Cons: In JavaScript, when you create an array with the `Array` constructor, it returns an instance of `Array`, which is a constructor function. This might lead to some overhead due to the need to create a function call.

*   Accessing the length property of an existing array:
    *   Pros: It's more concise and doesn't require creating a new object or using the `Array` constructor.
    *   Cons: When you use this method, you're accessing a property of an array. This might incur additional overhead due to the need to check whether the value is numeric.

**Library and purpose**

There are no libraries being used in these tests. The tests only rely on built-in JavaScript functionality.

However, there's a library called 'MeasureThat' (not explicitly mentioned but referenced by MeasureThat.net) that provides this functionality. This library seems like an extension for MeasureThat.net to help measure different types of JavaScript code performance.

There are no special JS features or syntax being tested in these examples.

**Alternative approaches**

Other approaches could be tested, such as:

*   Using `Array.from()` to create an empty array
*   Creating a new object with the `Object` constructor and then using the `length` property
*   Using a library like Lodash's `constant()` function to create an empty array

These alternatives would likely have similar performance characteristics, but might require additional setup or configuration.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.104 Safari/537.36

Browser/OS: Chrome 88 on Windows

View result in a separate tab

Test name	Executions per second
new array	3208175.0 Ops/sec
length	2907946.2 Ops/sec

Related benchmarks:

new array vs array length (version: 0)

Comparing performance of: new array vs length

Created: 3 years ago by: Guest

Jump to the latest result

new array

length

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):