Benchmark: fastest isArray - 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 popCase(obj) {
  return obj.pop 
}
var isArray = Array.isArray

Tests:

Array.isArray
isArray([])
instanceof
instCase([])
[].constructor
consCase([])
Object.prototype.toString
toStrCase([])
obj.pop
popCase([])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

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

**Benchmark Definition**

The benchmark compares five different approaches to check if an object is an array:

1. `Array.isArray()`
2. `Object.prototype.toString()` with a custom implementation (`toStrCase`) that checks for the string `[object Array]`.
3. `[] .constructor` (using the constructor property of the empty array)
4. `obj instanceof Array`
5. `obj.pop` (trying to access and remove an element from the object)

**Comparison Options**

The benchmark is comparing these five approaches in terms of performance, specifically the number of executions per second (`ExecutionsPerSecond`) on a specific device platform (Mobile, Android 8.0.0).

**Pros and Cons of Each Approach:**

1. `Array.isArray()`: This approach is straightforward and easy to implement. However, it may not be as efficient as other approaches since it requires calling the `Array.isArray()` method.
2. `Object.prototype.toString()` with custom implementation (`toStrCase`): This approach provides a way to check for an array type without relying on the `Array.isArray()` method. However, the custom implementation adds complexity and may not be optimized for performance.
3. `[] .constructor`: This approach uses the constructor property of the empty array to check if an object is an array. It's concise but may not be as efficient as other approaches since it relies on the constructor property being set correctly.
4. `obj instanceof Array`: This approach uses the `instanceof` operator to check if an object is an instance of the `Array` constructor. It's a common and straightforward way to check for array type, but its performance may vary depending on the browser and device.
5. `obj.pop`: This approach tries to access and remove an element from the object. If successful, it returns true; otherwise, it throws a `TypeError`. It's not a typical way to check if an object is an array.

**Library and Purpose:**

None of the approaches use any external libraries.

**Special JS Features or Syntax:**

The benchmark uses the following special JavaScript features:

* `instanceof` operator
* Custom implementation (`toStrCase`) for `Object.prototype.toString`

**Other Alternatives:**

If you need to check if an object is an array in JavaScript, some alternative approaches include:

1. Using a library like Lodash or Underscore.js, which provide utilities for working with arrays.
2. Using the `Array.isArray()` method only if the object has a `length` property and `Symbol.iterator` (for older browsers).
3. Using a more advanced approach like using a recursive function to check if an object is an array.

Note that these alternatives may have different performance characteristics or requirements, depending on the specific use case.

Related benchmarks:

fastest isArray (version: 0)

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

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

Created: 3 years ago by: Guest

Jump to the latest result

Array.isArray

instanceof

[].constructor

Object.prototype.toString

obj.pop

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):