Benchmark: isArray vs length (with alpha)

Script Preparation code:

function myIsArray(obj){
  return obj.length > 0;
}

var isArray = Array.isArray

Tests:

Array.isArray
isArray(["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"])
Check object.length
myIsArray(["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.isArray
Check object.length

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:143.0) Gecko/20100101 Firefox/143.0

Browser/OS: Firefox 143 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Array.isArray	31477040.0 Ops/sec
Check object.length	31399928.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what is being tested, compared, and the pros/cons of different approaches.

**Benchmark Definition**

The benchmark measures the performance difference between two ways to check if an object is an array:

1. `Array.isArray()`: This method checks if the object passed as an argument is an instance of the Array class.
2. `myIsArray()`: This custom function uses a simple check (`obj.length > 0`) to determine if the object is an array.

**Options Compared**

The benchmark compares two options:

1. Using the built-in `Array.isArray()` method
2. Writing a custom function `myIsArray()` to perform the same check

**Pros and Cons**

Using `Array.isArray()`:

Pros:

* Built-in method, likely optimized for performance
* Less code to write and maintain
* Less chance of errors due to incorrect implementation

Cons:

* May not be supported in older browsers or versions of JavaScript
* Can throw an error if passed a non-array value (although this is rare and usually caught with proper handling)

Using `myIsArray()`:

Pros:

* Allows for more control over the check, potentially leading to better performance
* Can be used in scenarios where `Array.isArray()` is not supported

Cons:

* Requires writing custom code, which can lead to errors or inefficiencies if not implemented correctly
* May not be optimized for performance compared to built-in methods

**Library and Custom Function**

The benchmark uses the built-in `Array` class and defines a custom function `myIsArray()`. The purpose of `myIsArray()` is to demonstrate an alternative approach to checking if an object is an array, while still achieving similar results as `Array.isArray()`.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax used in this benchmark. It only uses standard JavaScript concepts and built-in methods.

**Alternatives**

Other alternatives for checking if an object is an array could include:

* Using the `typeof` operator (`typeof obj === 'object' && Array.isArray(obj)`)
* Implementing a custom check using bitwise operations (`obj.length !== 0 && obj.constructor === Array`)
* Utilizing libraries like Lodash or Underscore.js, which provide utility functions for working with arrays

Keep in mind that the best approach will depend on the specific use case and requirements.

Related benchmarks:

isArray vs length (with alpha) (version: 0)

Array.isArray vs array.length > 0

Comparing performance of: Array.isArray vs Check object.length

Created: 3 years ago by: Guest

Jump to the latest result

Array.isArray

Check object.length

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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