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([])

Historical Performance Data aggregated from 33 community runs

Desktop Results:

Chrome 27 runs

Check object.length

31.9M/s

Array.isArray

31.8M/s

View exact numbers

✓ Check object.length: 31,940,142 ops/sec
• Array.isArray: 31,811,580 ops/sec

Firefox 6 runs

Check object.length

1570.3M/s

Array.isArray

343.0M/s

Fastest: Check object.length (4.6x faster)

View exact numbers

✓ Check object.length: 1,570,345,600 ops/sec
• Array.isArray: 343,048,896 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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: 7 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:146.0) Gecko/20100101 Firefox/146.0

Browser/OS: Firefox 146 on Windows

View result in a separate tab

Check object.length

2161.4M/s

Array.isArray

352.9M/s

View exact numbers

Test name	Executions per second
✓ Check object.length	2,161,383,168 Ops/sec
Array.isArray	352,865,728 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 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`)

isArray vs length (version: 0)

Array.isArray vs array.length > 0

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

Created: 4 years ago by: Guest

Go to the latest result

Array.isArray

Check object.length

Historical Performance Data aggregated from 33 community runs

Desktop Results:

Chrome 27 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

isArray vs length (version: 0)

Array.isArray vs array.length > 0

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

Created: 4 years ago by: Guest

Go to the latest result

Array.isArray

Check object.length

Historical Performance Data aggregated from 33 community runs

Desktop Results:

Chrome 27 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

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