Benchmark: isArray vs optional 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:

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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 Definition**
The benchmark is testing two approaches to check if an object is an array or not:

1. `Array.isArray`: This is a built-in JavaScript method that checks if an object is an array.
2. `myIsArray(obj)`: This is a custom function created for the benchmark, which returns `true` if the object has a `.length` property greater than 0.

**Pros and Cons of each approach:**

1. `Array.isArray`:
	* Pros:
		+ Built-in method, so it's likely to be implemented efficiently.
		+ Simple and concise.
	* Cons:
		+ May not work as expected for non-array objects that have a `.length` property.
2. `myIsArray(obj)`: (Custom function)
	* Pros:
		+ Flexible and can handle any object with a `.length` property, regardless of whether it's an array or not.
	* Cons:
		+ Not built-in, so its implementation might vary across different browsers and versions.

**Library: None**
There is no external library being used in this benchmark.

**Special JS feature/syntax:** `Optional Chaining (?.)` and Template Literals (`\r\n`) are being used in the `myIsArray` function. These features were introduced in ECMAScript 2020 (ES2020) standard:

* Optional Chaining: allows accessing nested properties using a dot (`.`) followed by a question mark (`?`). This syntax is optional, hence the `.?.length > 0` expression.
* Template Literals: allow using backticks (`\`) instead of double quotes to create string literals. In this case, it's used for multi-line code formatting.

**Other alternatives:**
If you wanted to write a similar `myIsArray` function without using optional chaining and template literals, you could use the following implementation:
```javascript
function myIsArray(obj) {
  return obj && typeof obj === 'object' && obj.length > 0;
}
```
This function checks if the object is truthy (`obj && ...`) and has a `.length` property that's greater than 0. However, it doesn't take advantage of optional chaining like the original implementation.

**Benchmark Preparation Code**
The preparation code sets up the custom `myIsArray` function in addition to the built-in `Array.isArray`. This allows for two separate test cases:

1. `isArray([])`: Tests if the built-in `Array.isArray` method returns false when given an empty array.
2. `myIsArray([])`: Tests if the custom `myIsArray` function returns true (indicating that the object has a `.length` property greater than 0, even though it's not an actual array).

These test cases provide insight into how different approaches compare in terms of performance and accuracy.

Related benchmarks:

isArray vs optional 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>

Fastest: N/A

Slowest: N/A

No previous run results

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