Benchmark: isArray-2 - MeasureThat.net

Script Preparation code:

var toStr = Object.prototype.toString
	
function toStrCase(obj){
  return toStr.call(obj) === '[object Array]'
}
function consCase(obj){
  return obj && obj.constructor === Array
}
function instCase(obj){
  return obj && obj instanceof Array
}
function boolCase(){
  return yes === true;
}
var yes = true;
var isArray = Array.isArray

Tests:

Array.isArray
isArray([])
instanceof
instCase([])
[].constructor
consCase([])
Object.prototype.toString
toStrCase([])
bool
boolCase()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.isArray
instanceof
[].constructor
Object.prototype.toString
bool

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.

I'll break down the provided benchmark and its test cases to explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The test suite measures performance differences between various methods for checking if an object is an array in JavaScript:

1. `Array.isArray()`
2. `Object.prototype.toString` with a custom check for `[object Array]`
3. `[].constructor` with a custom check for `Array`
4. `instanceof Array` (using the `instanceof` operator)
5. A simple boolean check (`boolCase()`)

**Options Comparison**

The test suite compares these five options to determine which one is the fastest. The pros and cons of each approach are:

1. **`Array.isArray()`**: This method is the most intuitive and widely used way to check if an object is an array. However, it might be slower than other methods due to its overhead.
	* Pros: Simple, readable, and widely supported.
	* Cons: May incur additional overhead compared to custom checks.
2. **`Object.prototype.toString`**: This method uses the `toString()` method of the `Array` prototype to check if an object is an array. It's a more low-level approach that can be optimized for performance.
	* Pros: Can be faster due to its low-level nature and potential for optimization.
	* Cons: Requires knowledge of the internal workings of JavaScript and may not work as expected in all cases.
3. **`[].constructor`**: This method uses the constructor property of the `Array` prototype to check if an object is an array. It's similar to the previous approach but uses a different mechanism.
	* Pros: Similar performance characteristics to `Object.prototype.toString`.
	* Cons: May not work as expected in some cases, especially with custom constructors.
4. **`instanceof Array`**: This method uses the `instanceof` operator to check if an object is an instance of the `Array` constructor.
	* Pros: Fast and efficient.
	* Cons: Requires a reference to the `Array` constructor (in this case, `Array.isArray`), which can introduce additional overhead.
5. **`boolCase()`**: This method uses a simple boolean check to determine if the value is true.
	* Pros: Extremely lightweight and fast.
	* Cons: Not suitable for this use case, as it doesn't actually check if an object is an array.

**Library Usage**

The `Array.isArray()` method uses the built-in `Array` prototype in JavaScript. The other methods rely on the internal workings of JavaScript or custom implementations.

**Special JS Features or Syntax**

The test suite does not explicitly mention any special JavaScript features or syntax, as all methods are based on standard language constructs (e.g., `instanceof`, `toString()`, and `constructor`). However, it's worth noting that some of these methods may rely on the internal workings of JavaScript or specific browser implementations.

**Alternatives**

Some alternative approaches to measuring this performance could include:

* Using a more specialized library like `is-array` (a lightweight polyfill for `Array.isArray()`).
* Implementing a custom implementation using bitwise operations or other low-level techniques.
* Using a different programming paradigm, such as functional programming with a custom array utility function.

Keep in mind that these alternatives may not be suitable for production use or may require significant development effort to implement correctly.

Related benchmarks:

isArray-2 (version: 0)

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

Comparing performance of: Array.isArray vs instanceof vs [].constructor vs Object.prototype.toString vs bool

Created: 2 years ago by: Guest

Jump to the latest result

Array.isArray

instanceof

[].constructor

Object.prototype.toString

bool

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):