Benchmark: isArray vs length

Script Preparation code:

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

Tests:

Array.isArray
isArray([])
Check object.length
myIsArray([])

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: 5 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1.1 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.isArray	500238560.0 Ops/sec
Check object.length	130770440.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what's being tested.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches to determine if an object is an array:

1. `Array.isArray`: This method checks if the object is an instance of the Array class, which is a built-in JavaScript constructor.
2. `myIsArray` (Check object.length): This is a custom implementation that simply returns true if the object has a length property and its value is greater than 0.

**Options Compared**

The two options being compared are:

* **Native Implementation (`Array.isArray`)**: The built-in method to check if an object is an array. It's implemented in native code and optimized for performance.
* **Custom Implementation (`myIsArray`)**: A custom function that checks if the object has a length property and its value is greater than 0.

**Pros and Cons**

**Native Implementation (Array.isArray)**

Pros:

* Fastest possible execution time, as it's implemented in native code.
* Most modern browsers will have this method optimized for performance.
* Fewer dependencies required, as it's built-in to the browser.

Cons: May not be compatible with older browsers or environments that don't support `Array.isArray`.

**Custom Implementation (myIsArray)**

Pros:

* Can provide a fallback solution for older browsers or environments that don't support `Array.isArray`.
* Can be optimized for specific use cases or performance requirements.
* Allows for more flexibility in implementation.

Cons:

* Slower execution time compared to the native implementation.
* Requires an additional dependency (the custom function definition).
* May require additional maintenance and updates as browsers evolve.

**Library Usage**

None of the provided test cases uses any libraries. The `Array.isArray` method is a built-in browser API, and the custom `myIsArray` function is defined in the benchmark preparation code.

**Special JS Feature or Syntax**

The benchmark doesn't utilize any special JavaScript features or syntax. It only focuses on comparing two different approaches to check if an object is an array.

**Other Alternatives**

If you wanted to test alternative implementations, you could consider:

* `instanceof` operator (not shown in the provided code)
* Using a library like Lodash (which has an implementation for `isArray`)

Related benchmarks:

isArray vs length (version: 0)

Array.isArray vs array.length > 0

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

Created: 2 years ago by: Guest

Jump to the latest result

Array.isArray

Check object.length

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):