Benchmark: (instanceof Function) vs (typeof function)

Script Preparation code:

function fun(x) { return x * 2; }

Tests:

instanceof
fun instanceof Function
typeof
typeof fun === 'function'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0

Browser/OS: Firefox 140 on Linux

View result in a separate tab

Test name	Executions per second
instanceof	86303824.0 Ops/sec
typeof	1504292224.0 Ops/sec

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 is being tested, compared, and the pros and cons of each approach.

**Benchmark Definition**

The benchmark definition JSON represents a simple JavaScript microbenchmark that compares two approaches:

1. `(instanceof Function)`: This checks if an object is an instance of the `Function` constructor.
2. `(typeof function)`: This checks if the result of applying the `typeof` operator to a function is `'function'`.

**Comparison**

The benchmark is comparing the performance of these two approaches in two test cases:

1. `fun instanceof Function`
2. `typeof fun === 'function'`

In other words, the benchmark is measuring how fast it can execute each comparison.

**Pros and Cons**

1. `(instanceof Function)`:
	* Pros:
		+ More precise and robust, as it checks if the object is an instance of the `Function` constructor.
	* Cons:
		+ May have a higher overhead due to the need to create a proxy or wrapper function to simulate the `Function` constructor.
2. `(typeof function)`:
	* Pros:
		+ Faster and more efficient, as it only needs to apply the `typeof` operator to the function.
	* Cons:
		+ May return incorrect results for certain edge cases (e.g., if the function is defined using a different syntax).

**Library Used**

In this benchmark, there is no explicitly mentioned library. However, the use of `(instanceof Function)` suggests that the test may be using some form of object creation or simulation to mimic the behavior of a function.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes being tested in this benchmark. The test cases only rely on basic JavaScript operators and constructs.

**Other Alternatives**

If you were to rewrite this benchmark, you might consider alternative approaches, such as:

1. Using `instanceof` with a more specific constructor (e.g., `new Function()`) to reduce overhead.
2. Creating a custom function or proxy to simulate the behavior of `(typeof function)`.
3. Using a different comparison operator (e.g., `===`) that may be faster or more efficient.

Keep in mind that the best approach will depend on the specific requirements and constraints of your use case.

As for the benchmark preparation code:
```javascript
function fun(x) { return x * 2; }
```
This code defines a simple function that takes a single argument `x` and returns its double value. The purpose of this function is to serve as a test subject for the comparison operators being tested.

Related benchmarks:

(instanceof Function) vs (typeof function) (version: 0)

Comparing performance of: instanceof vs typeof

Created: 4 years ago by: Guest

Jump to the latest result

instanceof

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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