Benchmark: checking empty array

Script Preparation code:

const arr = [{
    a: 2,
    b: 4
}, {
    a: 3,
    b: 6
}, {
    a: 5,
    b: 9
}]
const emptyArr = []

Tests:

useing isArray
const arr = [{ a: 2, b: 4 }, { a: 3, b: 6 }, { a: 5, b: 9 }] const emptyArr = []; if(Array.isArray(arr)) console.log('array'); if(Array.isArray(emptyArr)) console.log('emptyArray');
useing length
const arr = [{ a: 2, b: 4 }, { a: 3, b: 6 }, { a: 5, b: 9 }]; const emptyArr = []; if(arr?.length) console.log('array'); if(emptyArr?.length) console.log('emptyArray');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
useing isArray
useing length

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark measures the performance difference between two approaches to check if an object is an array: using `Array.isArray()` or checking the length of the object using the dot notation (`?.length`).

**Approach 1: Using `Array.isArray()`**

This approach checks if the input object is an instance of the `Array` class, which is a built-in JavaScript class. The `Array.isArray()` method returns a boolean value indicating whether the input is an array.

Pros:

* Simple and straightforward
* Easy to read and understand

Cons:

* Can be slower than other approaches due to the overhead of checking the constructor name
* May not work as expected with objects that have a `constructor` property set to `Array`

**Approach 2: Using Length Check (`?.length`)**

This approach checks if the input object has a `length` property, which is typically present in arrays. The dot notation (`?.`) is used to safely access the `length` property, returning `undefined` if it's not present.

Pros:

* Often faster than using `Array.isArray()`
* More concise and readable

Cons:

* May fail for objects that don't have a `length` property (e.g., dates, regex objects)
* Requires modern JavaScript features (ECMAScript 2018+)

**Library Used: None**

There are no external libraries used in this benchmark.

**Special JS Features/Syntax: None**

No special JavaScript features or syntax are being tested in this benchmark. The focus is solely on comparing two basic approaches to check if an object is an array.

**Other Alternatives**

Some alternative approaches to check if an object is an array include:

* Using `instanceof Array` (which is similar to using `Array.isArray()`)
* Checking the type of the object using `typeof arr === 'object'`
* Creating a new instance of `Array` and comparing it with the input object using `arr instanceof Array`

However, these alternatives are not included in the provided benchmark.

**Benchmark Preparation Code**

The benchmark preparation code creates an array of objects (`const arr`) and an empty array (`const emptyArr`). The script then checks if both arrays satisfy the condition using the two approaches being compared.

Related benchmarks:

checking empty array (version: 0)

isArray vs array.length

Comparing performance of: useing isArray vs useing length

Created: 2 years ago by: Guest

Jump to the latest result

useing isArray

useing length

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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