Benchmark: is type array - MeasureThat.net

Script Preparation code:

window.a = []
window.b = [1,2,3,4,5,6,7,8,9,10]
window.c = ['asdfasdf','2,3,4,5,6,7,8,9,10','asdfasf','adsfasdf','adfasdfdasf','adsfasdfas','asdfasfasdfasdfasdfasdfasdfasdfsadf']
window.d = null
window.e = undefined
window.f = 'adsfasdfasdf'
window.g = window
window.h = {123:123}

Tests:

instanceof
(function() { var bool if (a instanceof Array) bool = true if (b instanceof Array) bool = true if (c instanceof Array) bool = true if (d instanceof Array) bool = true if (e instanceof Array) bool = true if (f instanceof Array) bool = true if (g instanceof Array) bool = true if (h instanceof Array) bool = true })()
constructor ===
(function() { var bool if ((bool = a && a.constructor === Array) === true) bool = true if ((bool = b && b.constructor === Array) === true) bool = true if ((bool = c && c.constructor === Array) === true) bool = true if ((bool = d && d.constructor === Array) === true) bool = true if ((bool = e && e.constructor === Array) === true) bool = true if ((bool = f && f.constructor === Array) === true) bool = true if ((bool = g && g.constructor === Array) === true) bool = true if ((bool = h && h.constructor === Array) === true) bool = true })()
instanceof === true
(function() { var bool if ((a instanceof Array) === true) bool = true if ((b instanceof Array) === true) bool = true if ((c instanceof Array) === true) bool = true if ((d instanceof Array) === true) bool = true if ((e instanceof Array) === true) bool = true if ((f instanceof Array) === true) bool = true if ((g instanceof Array) === true) bool = true if ((h instanceof Array) === true) bool = true })()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
constructor ===
instanceof === true

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 its various components.

**Benchmark Definition JSON**

The provided JSON represents the benchmark definition, which includes:

1. **Name**: The name of the benchmark, in this case, "is type array".
2. **Description**: An empty description for the benchmark.
3. **Script Preparation Code**: A script that sets up variables `a`, `b`, `c`, `d`, `e`, `f`, `g`, and `h` on the global scope. These variables are used to test the `instanceof` operator.
4. **Html Preparation Code**: An empty HTML preparation code, which is not relevant for this JavaScript benchmark.

**Individual Test Cases**

The benchmark consists of three individual test cases:

1. **Test Case 1: "instanceof"**
This test case uses the `instanceof` operator to check if each variable (`a`, `b`, `c`, `d`, `e`, `f`, `g`, and `h`) is an instance of the Array type.
2. **Test Case 2: "constructor === true"**
This test case uses a variation of the `instanceof` operator, where the result of the comparison is assigned to the variable `bool`. This test case checks if the constructor property of each variable is equal to the Array constructor function (`Array.prototype.constructor`).
3. **Test Case 3: "instanceof === true"**
This test case uses a simplified version of the `instanceof` operator, where only the result of the comparison is checked (i.e., it's not assigned to any variable).

**Library and Purpose**

In this benchmark, there are no explicit libraries mentioned. However, some built-in JavaScript features are used:

* The `Array` constructor function (`Array.prototype.constructor`)
* The `instanceof` operator
* The `===` operator for value equality

**Pros and Cons of Each Approach**

Here's a brief analysis of each approach:

1. **Test Case 1: "instanceof"**
	* Pros:
		+ Simple and straightforward
		+ Easy to understand and implement
	* Cons:
		+ May not accurately reflect real-world scenarios, where the `constructor` property is often overridden or set to a different value.
2. **Test Case 2: "constructor === true"**
	* Pros:
		+ More accurate than `instanceof`, as it checks for exact constructor equality
	* Cons:
		+ Less intuitive and harder to understand, especially for developers without prior experience with JavaScript
3. **Test Case 3: "instanceof === true"**
	* Pros:
		+ Similar to Test Case 1 but with an added layer of complexity (value comparison)
	* Cons:
		+ May not be accurate or consistent in certain cases, as it depends on the specific values being compared

**Other Considerations**

When running this benchmark, consider the following:

* The `instanceof` operator's behavior may vary across different JavaScript engines and browsers.
* The `constructor` property can be overridden or set to a different value using various methods (e.g., `Object.defineProperty()`).
* Test cases should cover different scenarios, such as null, undefined, and primordial values.

**Alternatives**

Some alternative approaches could include:

* Using a more precise method for checking array type, such as `Array.isArray()`
* Adding additional test cases to cover edge cases (e.g., nested arrays, objects with array properties)
* Using a framework like Jest or Mocha for benchmarking and reporting
* Running the benchmark on multiple platforms and browsers to ensure consistency.

Related benchmarks:

is type array (version: 3)

Comparing performance of: instanceof vs constructor === vs instanceof === true

Created: 7 years ago by: Registered User

Jump to the latest result

instanceof

constructor ===

instanceof === true

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):