Benchmark: isArray3 - MeasureThat.net

Script Preparation code:

var array = [
    [1, 2, 3],
    [1, 2, 3], undefined, [1, 2, 3]
]

function isDefined(obj) {
    return obj !== undefined
}

function isThere(obj) {
    return obj
}

var isArray = Array.isArray

Tests:

Array.isArray
isArray(array[2])
isThere
isThere(array[2])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.isArray
isThere

Fastest: N/A

Slowest: N/A

Latest run results:

No previous 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 dive into the world of JavaScript microbenchmarks!

**Benchmark Overview**

The provided JSON represents a benchmark that tests three different approaches to check if an object is an array: `Array.isArray`, `Object.prototype.toString`, and `[] .constructor`. The test also includes two additional checks: `isThere` (which simply returns the object) and `undefined` (which checks for undefined objects).

**Options Compared**

The benchmark compares the performance of four different approaches:

1. `Array.isArray`: A built-in JavaScript method that returns a boolean indicating whether an object is an array.
2. `Object.prototype.toString`: A method on the `Object` prototype that returns a string representation of an object, which can be used to check if an object is an array.
3. `[] .constructor`: This approach uses the `Array` constructor and checks if the object's constructor is equal to `Array`.
4. `isThere`: A simple function that returns the object itself (which will always return a truthy value).
5. `undefined`: A check for undefined objects.

**Pros and Cons of Each Approach**

Here's a brief analysis of each approach:

1. **`Array.isArray`**:
	* Pros: Fast, reliable, and widely supported.
	* Cons: May not work as expected with non-array objects that have an array-like behavior (e.g., `arguments`, `String.prototype.slice()`).
2. **`Object.prototype.toString`**:
	* Pros: Works for most cases, including arrays, non-array objects, and null/undefined values.
	* Cons: May be slower than `Array.isArray` due to the overhead of creating a string representation.
3. **`[] .constructor`**:
	* Pros: Similar speed to `Array.isArray`, but may work in some edge cases where `Array.isArray` fails.
	* Cons: Less reliable and less readable than `Array.isArray`.
4. **`isThere`**: 
	* Pros: Fast, simple, and widely supported (as it always returns a truthy value).
	* Cons: Not a valid way to check if an object is an array, as it doesn't provide any meaningful result.
5. **`undefined`**:
	* Pros: None, as this approach is not applicable to checking if an object is an array.

**Library and Special JS Features**

In the provided benchmark, no libraries are used. However, `Array.isArray` uses a built-in JavaScript method, while `Object.prototype.toString` relies on the `Object` prototype's methods.

No special JavaScript features (e.g., `async/await`, `for...of`) are used in this benchmark.

**Alternatives**

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

* Using a library like Lodash or Underscore.js, which provide a robust set of utility functions.
* Implementing a custom check using bitwise operations (e.g., `Array.isArray` uses the `[[Array]]` property).
* Using a more advanced approach like checking for the presence of certain array-like properties (e.g., `hasOwnProperty('length')`).

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

Related benchmarks:

isArray3 (version: 0)

Array.isArray vs Object.prototype.toString vs [].constructor vs instanceof

Comparing performance of: Array.isArray vs isThere

Created: 5 years ago by: Guest

Jump to the latest result

Array.isArray

isThere

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):