Benchmark: instanceof vs typeof function

Script Preparation code:

var fn = function(){return 42}

Tests:

instanceof
fn instanceof Function
typeof
typeof fn === '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: 5 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser/OS: Chrome 142 on Windows

View result in a separate tab

Test name	Executions per second
instanceof	165413728.0 Ops/sec
typeof	284996128.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation.

The provided JSON represents two individual test cases for measuring the performance of JavaScript microbenchmarks on MeasureThat.net. Here's what each section tests:

**Benchmark Definition:**

* The first line specifies the name and description of the benchmark, which is "instanceof vs typeof function."
* However, there is no actual code to execute; instead, a script preparation code (`var fn = function(){return 42}`) and an html preparation code are provided. This suggests that the benchmark is testing the performance difference between using `instanceof` and `typeof` operators on a specific JavaScript function.

**Script Preparation Code:**

The script preparation code defines a simple JavaScript function named `fn`, which returns the value `42`. This function will be used as input for both test cases.

**Individual Test Cases:**

There are two individual test cases:

1. **Test Case 1: "instanceof"**
	* Benchmark Definition: `fn instanceof Function`
	* Purpose: To measure the performance of using the `instanceof` operator to check if the function `fn` is an instance of the `Function` constructor.
2. **Test Case 2: "typeof"**
	* Benchmark Definition: `typeof fn === 'function'`
	* Purpose: To measure the performance of using the `typeof` operator to check if the variable `fn` is a function.

**Pros and Cons:**

1. **Using `instanceof`**: This approach can be more precise for checking if an object is an instance of a specific constructor, but it may incur additional overhead due to the need to search the prototype chain.
2. **Using `typeof`**: This approach is generally faster and more concise, as it only checks the type of the variable without searching the prototype chain.

**Library/Functions Used:**

None of the test cases use external libraries or functions beyond JavaScript's built-in operators (`instanceof`, `typeof`, and the `Function` constructor).

**Special JS Features/Syntax:**

There are no specific special features or syntax mentioned in the benchmark. However, it's worth noting that the use of the `===` operator for equality checks is a common feature of modern JavaScript.

**Other Alternatives:**

If you're interested in measuring performance differences between other methods for checking function types, some alternative approaches could include:

* Using a regex to extract the type of the variable (e.g., `/^function/`)
* Creating a custom function to check if an object is a certain type
* Using a library or framework that provides a more precise way of checking function types

Keep in mind that these alternatives may not be as simple or straightforward as using `instanceof` and `typeof`, and their performance characteristics may vary depending on the specific use case.

Related benchmarks:

instanceof vs typeof function (version: 0)

Comparing performance of: instanceof vs typeof

Created: 3 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):